'Iceberg' was the US seizure of the large island of Okinawa, the smaller island of Ie-shima off Okinawa’s west coast, and the still smaller islands of the Kerama-retto off Okinawa’s south coast (1 April/22 June 1945).
Lasting 82 days, the battle for Okinawa was fought between 1 April and 22 June 1945. After a long campaign of island hopping, the forces of Admiral Chester W. Nimitz’s Pacific Ocean Areas command were approaching the Japan home islands, and planned to seize Okinawa, a large island only 340 miles (545 km) away from the home islands, for rapid development as the base for air attacks in support of the planned 'Downfall' conquest of the home islands, which was to start with 'Olympic' and proceed to 'Coronet' with combined US Army, US Marine Corps and US Navy forces under the overall command of General Douglas MacArthur.
Six divisions of Lieutenant General Simon B. Buckner’s US 10th Army fought on the island: these were the US Army’s 7th, 27th, 77th and 96th Divisions and the US Marine Corps' 1st and 6th Marine Divisions. The invasion and subsequent land campaign were supported by naval, amphibious and tactical air forces.
The campaign resulted in the largest number of casualties in the Pacific theatre of World War II. Based on Japanese official sources, mainland Japan lost 77,166 soldiers killed or committed suicide, and the US forces 14,009 men killed within an estimated total of more than 65,000 casualties of all kinds. The campaign also saw the deaths of between 42,000 and 150,000 civilians killed or committed suicide.
The 'Silverplate' and 'Centerboard' atomic bombings of Hiroshima and Nagasaki on 6 and 9 August combined with the Soviet 'Avgust Buri' invasion of Manchukuo, Inner Mongolia, northern Korea etc. from 8 August finally convinced Japan to surrender less than two months after the end of the fighting on Okinawa.
Possessing the anchorages and the land for airfield construction and the build-up of men and supplies desired by the US forces, Okinawa is the largest and most important island of the Ryukyu group between Japan and Formosa. It is some 64 miles (103 km) long and between 2 and 18 miles (3.2 to 29 km) wide. Two-thirds of the island, to the north of the Ishikawa isthmus, are comparatively rugged, with the terrain rising to a maximum height of 1,650 ft (503) at Mt Yonaha, covered with heavy forest, and possessing a single one-lane road. The area to the south from the small port of Naha is characterised by coral ridges up to a height of 500 ft (150 m), but the area to the north of Naha had considerable areas of flat terrain suitable for the construction of airfields and barracks. It was this last which made Okinawa the natural staging area for the planned invasion of Japan. Almost the whole of the island’s land transport network comprised one-lane roads and trails, however, and only a very small portion of this network was surfaced, with crushed coral, and all of it was underlain by clay incapable of sustaining heavy military traffic in rainy weather. There were also some 30 miles (48 km) of narrow-gauge railway linking Naha with Kadena airfield and other points in the south of the island: two of these three railway lines were for horse- rather than locomotive-drawn wagons.
Much of the coast comprises coral cliffs with numerous coral heads. However, the coast to the west of Kadena has a coral reef some 200 to 700 yards (185 to 640 m) offshore, and this could be crossed by trucks at low tide. It was this area which the US forces selected for their landings because the beaches were suitable and because Kadena and Yontan airfields, located just 2,000 yards (1830 m) inland, could be quickly seized for land-based fighters to help provide cover for the invasion fleet. The Americans dubbed these the Hagushi beaches after a small village located close to the boundary between the US Army and US Marine sectors. Nakagusuku Bay, on the south-eastern quadrant of the island and which the Americans later renamed Buckner Bay also possessed some suitable landing beaches. The Japanese were aware of this, and therefore located a heavy artillery fortress regiment there.
Okinawa’s climate is characterised by moderate temperatures between 4.5° and 29.5° C (40° and 85° F) and high humidity, and the annual precipitation is some 93 in (2.36 m) per year, most of it falling in the wet season between May and September.
In 1945 the island possessed a population in the order of 435,000 persons, the great majority of them living in the southern one-third of the island, of which four-fifths was farmland producing sweet potatoes, sugar, rice and soya beans. About 60,000 children and 20,000 other civilians were evacuated by ship, and another 60,000 relocated into the rugged north away from the anticipated battleground in southern Okinawa. Of those that remained, some 100,000 are estimated to have died during the Okinawa campaign, during which about 25,000 were conscripted into the army.
During the evacuation, a transport vessel was sunk by an US submarine with the loss of 700 school children. The other 186 vessels involved in the evacuation were unscathed.
In addition to the two main airfields at Yontan and Kadena, there was the smaller Machiano airfield just to the north of Naha, the abandoned Yonabaru airfield to the east of Machiano, a naval airfield on the Oroku peninsula to the south of Naha, and two airfields on the island of Ie Shima to the west of the main island’s Motobu peninsula.
About 15 miles (24 km) to the west of the southern end of Okinawa is the Kerama-retto, a group of small and hilly islands measuring about 7 by 13 miles (11.25 by 21 km) with a maximum elevation of 787 ft (240 m). The terrain is unsuitable for airfield construction but the islets surround a deep protected anchorage large enough to accommodate 75 major ships and with two entrance channels which could easily be defended with nets. There was also a site suitable for seaplane operations in the Aka Channel.
Okinawa has an area of 464 sq miles (1202 km˛), and from the middle of the Pacific campaign was deemed by the Americans to be one of the base area most suitable for the launch of the invasion planned against the Japan homeland.
It was on 3 October 1944 that the US Joint Chiefs-of-Staff ordered Nimitz’s Pacific Ocean Areas command to take one or more of the Ryukyu islands by 1 March 1945. It was fully appreciated by the US high command that 'Iceberg' would be both difficult and costly as the island was well defended and possessed a large civilian population, lay comparatively close to the Japan home islands and could thus be reinforced with comparative ease before the actual invasion, and would be defended with more than the normal fanaticism as it was regarded as an organic part of Japan by its defenders.
US planning for the Okinawa campaign began with a preliminary study by Nimitz’s Pacific Ocean Areas staff dated 25 October 1944. Capture of the island was seen as an alternative to seizing Formosa, and would provide the Allies with a staging area close to Kyushu for the final invasion of Japan. Final planning began on 24 November 1944 between Rear Admiral Lawrence F. Reifsnider as the amphibious group commander, Vice Admiral Richmond K. Turner as the amphibious force commander, Buckner as the 10th Army commander, and Major General Roy S. Geiger as the III Amphibious Corps commander. Other senior US commanders included Rear Admiral John L. Hall as the commander of the amphibious group to land the XXIV Corps, and Rear Admiral Morton L. Deyo as the bombardment force commander.
The plan to take Okinawa was bold and perhaps risky. Okinawa lies 800 miles (1285 km) from the nearest airfields then occupied by the Allies, and this meant that the invasion would be almost completely reliant on cover by carrierborne aircraft. The invasion force would be within easy kamikaze range of both Formosa and Kyushu, and Allied intelligence estimated that the Japanese could concentrate as many as 3,000 aircraft against the landings. Nimitz wanted support by Boeing B-29 Superfortress heavy bombers against the kamikaze airfields, but this was bitterly resisted by Major General Curtis E. LeMay, commander of the XXI Bomber Command in the Mariana islands Group an unacceptable diversion from their strategic bombing role. Nimitz succeeded in getting two B-29 missions flown against the kamikaze airfields, on 29 and 31 March. These badly damaged the airfields, and a simultaneous aerial mining mission closed the Shimonoseki Strait for one week.
The 'Iceberg' campaign for Okinawa was the largest amphibious assault undertaken during the Pacific campaign of World War II, and was also the largest combined land, sea and air battle of history. Neither the Americans nor the Japanese anticipated that this would be the final battle of the Pacific war, which in fact it became.
In some of the battles of the Pacific campaign, including major undertakings such as 'Detachment' which led to the battle for Iwo Jima, there had been no civilian involvement. But Okinawa had a large indigenous population, whose losses in 'Iceberg' were between 42,000 and 150,000, the latter figure representing more than 40% of a civilian population of 355,000 remaining after 80,000 had been shipped to Kyushu as labourers. The overall figure for US losses was more than 90,150 men, of whom 7,950 ground troops were killed or missing but without several thousand soldiers who later died from wounds and other causes. More than 100,000 Japanese soldiers were killed, and some 7,400 were taken prisoner. Some of the soldiers committed suicide, as did a not inconsiderable number of the civil population, convinced by Japanese propaganda that the Americans were barbarians who would commit terrible atrocities, and thus opted to kill their families and themselves to avoid capture.
'Iceberg' was designed along the amphibious warfare lines perfected in preceding Pacific campaigns, and was entrusted to the Central Pacific Task Forces under Admiral Raymond A. Spruance, who was also commander of both the US 5th Fleet and its main operational element, Task Force 50 (Covering Forces and Special Groups). Subordinate to the 5th Fleet was Turner’s Joint Expeditionary Force (TF51) which comprised Rear Admiral William H. P. Blandy’s Amphibious Support Force (TF52 with escort carriers, gunboats and minesweepers), Deyo’s Gunfire and Covering Force (TF54 with 10 older battleships, 11 cruisers and 30 destroyers), Reifsnider’s Northern Attack Force (TF53 to deliver the III Amphibious Corps), Hall’s Southern Attack Force (TF55 to deliver the XXIV Corps), Demonstration Group (TG51.2 with the 2nd Marine Division) and Buckner’s Expeditionary Troops (TF56).
This last was the largest single element of TF50, and comprised Buckner’s 10th Army of two corps, namely Geiger’s 88,500-man III Amphibious Corps comprising Major General Pedro A. del Valle’s 1st Marine Division (1st, 5th and 7th Marines plus the 11th Marine Artillery) and Major General Lemuel C. Shepherd’s 6th Marine Division (2nd, 6th and 8th Marines plus the 10th Marine Artillery) with Major General Thomas E. Watson’s 2nd Marine Division (4th, 22nd and 29th Marines plus the 15th Marine Artillery) as the afloat reserve; and Major General John B. Hodge’s 102,250-man (finally 190,300-man) XXIV Corps comprising Major General Archibald V. Arnold’s 7th Division (17th, 32nd and 184th Infantry), Major General George W. Griner’s 27th Division (105th, 106th and 165th Infantry) earmarked as the garrison of the island after its capture had been completed, Major General Andrew D. Bruce’s 77th Division (305th, 306th and 307th Infantry) and Major General James L. Bradley’s 96th Division (381st, 382nd and 383rd Infantry). In reserve on New Caledonia was Major General Paul J. Mueller’s 81st Division (321st, 322nd and 323rd Infantry), which was in the event not committed.
In all, the US Army deployed than 102,000 men, of whom more than 38,000 were non-divisional artillery, combat support and headquarters troops, and another 9,000 service troops; the US Marine Corps more than 88,000 men; and the US Navy more than 18,000 men in the form primarily of 'Seabee' construction and medical personnel. The plan was that Buckner would report to Turner until the amphibious phase was completed, after which he would report directly to Spruance.
Both the III Amphibious Corps and XXIV Corps had substantial corps artillery and support assets, and additional 10th Army assets were the 53rd Anti-Aircraft Artillery Brigade and the 20th Armored Group.
The war first came to the Okinawa-gunto in a direct fashion on 29 September 1944, when Boeing B-29 Superfortress heavy bombers attacked its airfields. The first raid by carrierborne aircraft followed, on 10 October, as an attempt primarily to neutralise the Japanese air threat to the US invasion forces approaching Leyte for 'King II'. The Japanese referred to this action as the Air Battle of Formosa, and lost 500 aircraft as well as some 35 ships in three days.
Okinawa was then granted a respite until the start of 1945, when there was a major raid on 3 January by the aircraft of the Fast Carrier Task Force, which returned on 10 January for an even more punishing raid. The January operations were undertaken in conjunction with raids on Formosa and the coast of China. The Fast Carrier Task Force also struck at targets in the area of Tokyo right through a time late in February. While retiring to Ulithi atoll after this effort, the Fast Carrier Task Force struck Okinawa on 1 March with a notably devastating raid.
By this time US submarines and patrol bombers had effectively isolated the Ryukyu islands from Japan and Formosa, sinking large numbers of cargo ships.
Between their attacks on Japan, the B-29 bombers flew many raids against targets on Okinawa, and by the end of March 1945 there were almost no operational Japanese aircraft in the Ryukyu islands group. Naha City and its port had been completely destroyed, as had Shuri.
On 14 March Vice Admiral Marc A. Mitscher’s TF58 departed from Ulithi atoll where, on 11 March, the fleet carrier Randolph had been severely damaged by a kamikaze aeroplane. Rear Admiral Joseph J. Clark’s TG58.1 comprised the fleet carriers Hornet, Wasp and Bennington, the light carriers Belleau Wood and San Jacinto, the battleships Massachusetts and Indiana, the heavy cruisers Baltimore and Pittsburgh, the light cruisers Vincennes, Miami, Vicksburg and San Juan, and the 15 destroyers of Destroyer Squadrons 25 and 61 (John Rodgers, Harrison, McKee and Murray of Destroyer Division 49, Sigsbee, Ringgold, Schroeder and Dashiell of Destroyer Division 50, De Haven, Mansfield, Lyman K. Swenson and Collett of Destroyer Division 121, and Maddox, Blue, Brush, Taussig and Samuel N. Moore of Destroyer Division 122. Rear Admiral Ralph E. Davison’s TG58.2 comprised the fleet carriers Enterprise and Franklin, the light cruiser Santa Fe, and 10 destroyers of Destroyer Division 52 (Twining, Hunt, Wedderburn, English and Waldron, Stephen Potter, The Sullivans and Tingey of Destroyer Division 103, and Marshall and Hickox of Destroyer Division 104; Rear Admiral Frederick C. Sherman’s TG58.3 comprised the fleet carriers Essex, Bunker Hill and Hancock, the light carriers Cabot and Bataan, the battleships Washington, North Carolina and South Dakota, the heavy cruiser Indianapolis, the light cruisers Pasadena, Springfield, Astoria and Wilkes-Barre, and 17 destroyers of Destroyer Squadrons 48 and 62 (Erben, Walker, Hale and Stembel of Destroyer Division 95, Black, Bullard, Kidd and Chauncey of Destroyer Division 94, Ault, English, Charles S. Sperry, Waldron and Haynsworth of Destroyer Division 123, and Wallace L. Lind, John W. Weeks, Hank and Borie of Destroyer Division 124; and Rear Admiral Arthur W. Radford’s TG58.4 comprised the fleet carriers Yorktown and Intrepid, the light carriers Langley and Independence, the battleships Wisconsin, Missouri and New Jersey, the super-heavy cruisers Alaska and Guam, the light cruisers St Louis, Flint, Oakland and San Diego, and the 21 destroyers of Destroyer Squadrons 47, 53, 54 and 62 (McCord, Trathen, Hazelwood and Heermann of Destroyer Division 93, Haggard, Franks and Hailey of Destroyer Division 94, Cushing, Colahan, Uhlmann and Benham of Destroyer Division 105, Twining of Destroyer Division 106, Remey, Norman Scott, Mertz, Melvin and McGowan of Destroyer Division 107, McNair, and McDermut, Monssen and Wadleigh of Destroyer Division 108.
After refuelling on 16 March, the US carriers launched a heavy attack early on 18 March against targets on Kyushu, concentrating their efforts mainly on airfields but also sinking six ships and damaging another three. The US aircrews met few Japanese aircraft in the air or on the ground, although reconnaissance aircraft discovered a concentration of warships, including the super-battleship Yamato, in the Inland Sea. The Japanese had detected the incoming US attackers and had therefore dispersed their aircraft or had them in the air.
Under the command of Vice Admiral Matome Ugaki’s 5th Air Fleet, 48 kamikaze aircraft were despatched to attack the US carriers, although 18 of these aircraft did not find their targets and returned. The main attack was directed against TG58.4, and the kamikaze aircraft succeeded in lightly damaging Enterprise and Yorktown.
On 19 March the carrier air groups concentrated their attacks on the Japanese bases round the Inland Sea, with emphasis on Kure. There the Japanese light carriers Amagi, Katsuragi, Ryuho, Hosho, Kaiyo and new Ikoma, super-battleship Yamato, battleships Hyuga and Haruna, heavy cruiser Tone, light cruiser Oyodo, escort destroyers Kaki and Shinnan, landing ship T-105 and new submarines I-400, I-205 and Ro-67 were damaged.
A Japanese bomber formation of the 5th Air Fleet obtained a hit on Wasp, which caught fire and lost 101 men dead and 269 injured even though the fire was brought under control within 15 minutes, and scored two hits on Franklin at a moment when her hangar was full of aircraft being readied for an attack: a series of at least six secondary explosions severely damaged the flight deck of the carrier, which also caught fire and suffered heavy damage as the result of bomb and ammunition explosions. The carrier suffered the loss of 724 men killed and 265 injured. The cruiser Santa Fe and destroyer Hickox were damaged while alongside, and some 1,700 survivors were rescued by Santa Fe and Pittsburgh. Her captain was able to get the very badly damaged carrier under control again and, later, to bring her into New York under her own steam. The repairs were not completed until after the Japanese surrender.
Some 39 kamikaze aircraft, of which 20 returned, inflicted less severe damage on Enterprise, while Essex was damaged by self-inflicted anti-aircraft fire.
As the force withdrew on 20 March, and as the destroyers were being refuelled, the destroyer Halsey Powell was hit by a kamikaze aeroplane which had missed Hancock and inflicted moderate damage. Another damaged the planeguard submarine Devilfish.
On 21 March Japanese reconnaissance aircraft maintained contact with TF58, and 18 Mitsubishi G4M 'Betty' twin-engined bombers each carrying one Okha rocket-powered manned kamikaze aeroplane, together with 55 conventional kamikaze aircraft and 15 escorting fighters were launched. Some 45 of the conventional kamikaze aircraft and three of the fighters returned. The attacking force was located and intercepted by about 150 Grumman F6F Hellcat fighters some 60 miles (100 km) from its targets, and the heavily laden G4M motherplanes proved easy prey for the defending fighters, which shot down all but one of the attacking aircraft.
On 22 March TF58 met its oiler group and refuelled. In the process, the task groups, as a result of their losses, were distributed in three new groups: TG58.1 now comprised Hornet, Bennington, Belleau Wood, San Jacinto, Massachusetts, Indiana, Vincennes, Miami, Vicksburg and San Juan; TG58.3 comprised Essex, Bunker Hill, Hancock (later Shangri-La), Bataan, South Dakota, New Jersey, Pasadena, Springfield, Astoria and Wilkes-Barre; and TG58.4 comprised Yorktown, Intrepid, Enterprise, Langley, Wisconsin, Missouri, Alaska, Guam and San Diego.
The damaged Wasp and Franklin were escorted to Ulithi by Independence, Washington, North Carolina, Baltimore, Pittsburgh, Santa Fe, Flint and Oakland.
Between 18 and 31 March, carrierborne warplanes flew more attacks on the airfields of Kyushu island, the southernmost of the Japanese home islands, and Japanese warships in preparation for 'Iceberg'.
By 23 March the carriers were in position to launch their final series of raids on Okinawa itself. Greatly overestimating the damage done by their kamikaze aircraft and hampered by the damaging B-29 raids on their airfields, the Japanese reacted only slowly, and major kamikaze attacks in the waters around Okinawa did not begin until six days after the first landings.
This final series of carrier raids included a notably thorough programmer of aerial reconnaissance, and the resulting photographs served to indicate just how hard an objective Okinawa might prove to be. The reconnaissance revealed that the whole island was honeycombed with caves, tunnels and gun positions, and spotted armoured fighting vehicles taking cover in cave entrances. Mitscher forwarded this information to Turner on 26 March along with reassurances that TF58 would provide all possible air cover.
On 24 March Mitscher launched an attack by 112 aircraft against a convoy spotted 150 miles (240 km) to the north-west of Okinawa, and all eight of the convoy’s eight ships, including the torpedo boat Tomozuru and corvette Kaibokan 68, were sunk.
On 27/28 March TF58 replenished, the destroyer Murray being damaged by a lone Japanese aeroplane. On 28 March the corvette Kaibokan 33 was sunk by aircraft from Hornet. On 29 March TG58.4 again attacked Okinawa, while TG58.1 and TG58.3 attacked targets in the northern parts of the Ryukyu islands and on Kyushu. On 30/31 March TG58.1 replenished, while TG58.3 and TG58.4 made more attacks around and to the north of Okinawa. On 31 March the cruiser Indianapolis and minelaying destroyer Adams were damaged by kamikaze aircraft, as too were a transport vessel, LST-724 and LST-884. The cruiser Pensacola was damaged in a collision with LST-277.
Vice Admiral Sir Bernard Rawling’s British Pacific Fleet (TF57) departed the major anchorage in Ulithi atoll on 23 March and replenished at sea on 25 March. Carrierborne aircraft of Vice Admiral Sir Philip Vian’s carrier force attacked the islands of the Sakishima-gunto in the southern part of the Ryukyu group on 26/27 March in order to neutralise the airfields there. For this 'Iceberg I', the British task force comprised the fleet carriers Illustrious, Indefatigable, Indomitable and Victorious, the battleships Howe and King George V, the light cruisers Swiftsure and New Zealand Gambia, the light anti-aircraft cruisers Argonaut, Black Prince and Euryalus, and the destroyers Grenville, Ulster, Undine, Urania, Undaunted, Quickmatch, Quiberon, Queenborough, Kempenfelt, Whirlwind and Wager.
Between 28 and 30 March TF57 the British ships replenished from a supply group comprising of the escort carriers Striker and Speaker, sloops Crane and Pheasant, frigate Findhorn, three oilers, and destroyers Quality and Whelp, which relieved Kempenfelt and Whirlwind.
On 31 March the British force resumed its attacks in 'Iceberg II' to neutralise Japanese bases in the Sakishima-gunto.
On 24/25 March the units of Blandy’s TF52 and Deyo’s TF54 arrived off Okinawa. Three escort carrier groups of Rear Admiral Calvin T. Durgin’s TG52.1 supported the air attacks of TF58 and TF57, and assumed the fleet carriers' tasks, as best they could, while the larger carriers were being replenished. Involved were Durgin’s own Group 1 with the escort carriers Makin Island, Fanshaw Bay, Lunga Point, Sangamon, Natoma Bay, Savo Island and Anzio, the destroyers Ingraham, Hart, Boyd, Bradford, Patterson and Bagley of Destroyer Division 120, and the destroyer escorts Lawrence C. Taylor, Melvin R. Newman, Oliver Mitchell, Robert F. Keller, Tabberer, Richard M. Rowell, Richards, Bull, Dennis, Sederstrom, Fleming and O’Flaherty; Rear Admiral Felix B. Stump’s Group 2 with the escort carriers Saginaw Bay, Sargent Bay, Marcus Island, Petrof Bay, Tulagi and Wake Island, the destroyers Capps, Lowry, Evans and John D. Henley of Destroyer Division 19, and the destroyer escorts William Seiverling, Ulvert M. Moore, Kendall C. Campbell, Goss, Tisdale and Eisele; and Rear Admiral William D. Sample’s Group 3 with the escort carriers Suwanee, Chenango, Santee and Steamer Bay, and the destroyer escorts Edmonds and John C. Butler.
The preliminary naval bombardment by Blandy’s and Deyo’s task forces began on 25 March and continued for a full eight days. The bombardment force included 10 older battleships, seven heavy cruisers, three light cruisers, 24 destroyers, eight destroyer escorts, and 53 landing craft converted to rocket or mortar ships. Total ammunition expenditure in the week before the landings was 1,033 16-in (406-mm), 3,285 14-in (356-mm), 567 12-in (305-mm), 3,750 8-in (203-mm), 4,511 6-in (152-mm) and 27,266 5-in (127-mm) shells. There were also 3,000 aircraft sorties. The primary effect of the bombardment on the Japanese defenders of Okinawa was a raising of their morale by increasing their confidence in the strength of their fortifications. However, this bombardment probably killed tens of thousands of civilians without the benefit of the fortifications shielding the troops, and levelled all but one of Naha’s buildings.
On 24 March the minesweeping group, TG52.2 commanded by Rear Admiral Alexander Sharp on board the minelayer Terror, started to sweep with three groups of fast minesweepers (Forrest, Hobson, Macomb, Dorsey and Hopkins; Ellyson, Hambleton, Rodman and Emmons; and Butler, Gherardi, Jeffers and Harding), seven groups of 36 fleet minesweepers, and four groups each of six motor minesweepers. Each of these had one fast minelayer allocated for temporary support from the following: Gwin, Lindsey, Aaron Ward, Adams, Tolman, Henry A. Wiley, Shea, Tracy, J. William Ditter, Robert H. Smith, Shannon, Thomas E. Fraser, Henry F. Bauer and Breese.
By the time of the landings, the minesweeper force had swept 184 mines from six separate fields in an area of 2,500 sq miles (6475 km˛). During these operations, the destroyer Halligan hit a mine, and the resulting explosion set off her forward magazines and destroyed the ship with the loss of 153 men killed and 39 wounded out of a crew of 325 men. Skylark hit two mines and sank on 28 March, though with slight loss of life. The minelayer Adams was crippled by a kamikaze aeroplane on the day of the landings. The minecraft, which had to operate independently or in small groups and lacked point-defence weapons, eventually suffered more than 15% of all the naval casualties in the campaign.
Local air cover during the bombardment was provided by Durgin’s 18 escort carriers, while the fast carriers of Mitscher’s TF58 struck at distant airfields from which the Japanese might launch aircraft against the bombardment force. Shortly after dawn on 27 March, however, and before the US combat air patrol had formed up, a group of seven kamikaze aircraft fell on the bombardment force, inflicting moderate damage on the battleship Nevada and light damage on the light cruiser Biloxi. The destroyer O’Brien was severely damaged and forced out of the campaign, and the minesweeper Dorsey suffered light damage. Another Japanese raid on the night of 28 March was directed against small patrol craft and sank LSM(R)-188. Thereafter the escort carriers flew dawn interdiction sweeps against local Japanese airfields and put an end to the dawn raids.
As the bombardment continued, US intelligence officers puzzled over reports from spotting aircraft and other observers that there was now almost no sign of Japanese activity anywhere on Okinawa. Intelligence officers remained concerned about the possibility that as they landed, the US ground forces would come under a hail of enfilading fire from caves in the limestone bluffs overlooking and from pillboxes constructed around the airfields and along the sea wall, 6 to 7 ft (1.8 to 2.1 m) high, behind the beaches. The final phase of the bombardment saw an attempt to destroy these positions while creating breaches in the sea wall, but met with little success.
On 31 March a final attack by four kamikaze aircraft managed to cripple Spruance’s flagship, the heavy cruiser Indianapolis, and Spruance therefore transferred his flag to the battleship New Mexico.
On 25 March the underwater demolition teams of the Underwater Demolitions Flotilla (TG52.11), totalling 10 100-man teams, arrived on board 10 troop-carrying destroyer conversions, and began the task of clearing the assault beaches of underwater obstacles.
The main landings on Okinawa were preceded by the seizure of the Kerama-retto on 26 March by Bruce’s 77th Division. Turner had decided to take the anchorage which would thereby be provided to serve as a safe haven for warships damaged during the main assault. The idea initially received a very cool reception from staff officers worried about the lack of air cover for this effort, but Turner insisted on the operation, and the anchorage did indeed prove very useful during the Okinawa campaign.
The landing force was delivered by the vessels of Rear Admiral Ingolf N. Kiland’s Western Islands Attack Group (TG51.1) of 17 attack and attack cargo ships, 56 tank landing ships and a number of support vessels. The plan was to make simultaneous landings in force on five of the six largest islets. It was believed that there were between 1,000 and 1,500 Japanese troops on the islands, but this proved to be an overestimate.
Pre-landing bombardment for this smaller operation began on 26 March and was carried out by Rear Admiral Charles T. Joy with the cruisers San Francisco and Minneapolis, supported by three destroyers. Underwater demolition teams assessed the proposed landing beaches on the same day, and established that the beaches on the two outermost islands were unsuitable for anything but LVT amphibious tracked carriers. As none of these versatile machines could be spared, the landings of these small islands were postponed.
The landings in the Kerama-retto were covered by air attacks on the Miyako-retto by the fleet carriers of the British TF57, which had just arrived, and local combat air patrol was provided by aircraft operating from three US escort carriers. However, nine kamikaze aircraft broke through the defensive screen and attacked the landing force the evening of the landings, lightly damaging the destroyer Kimberly.
The battleship Arkansas was on hand to support the landing as and when required, and on 26 March the Western Islands Attack Group, with the headquarters ship Mount McKinley, landed Bruce’s 77th Division on the Kerama-retto, where only light resistance was met. The division was transported in and landed by a force of 13 attack transports, six attack cargo ships, 28 tank landing ships, 11 medium landing ships and eight support vessels escorted and supported, under the command of Captain Frederick Moosbrugger, by the headquarters ship Biscayne, destroyers Picking, Sproston, Wickes, William D. Porter, Isherwood, Kimberly, Luce and Charles J. Badger of Destroyer Squadron 49, and destroyer escorts Scribner, Kinzer, Richard W. Suesens, Abercrombie, Oberrender, Riddle, Swearer and Stern.
The remaining landing operations encountered no opposition as the defending Japanese troops had fled into the hills. Two counterattacks that night were repelled at a cost to the Japanese of 106 dead. On Geruma-shima, the Americans found 12 women and a number of children strangled by their own men, who had been worked into a terror of the Americans by Japanese propaganda.
Total casualties in the Kerama-retto campaign were 145 US personnel killed or missing and 211 wounded, the majority of them sailors. The Japanese lost about 530 killed and 121 taken prisoner. Some 300 Japanese remained at large in the hills of the Kerama-retto until the final Japanese surrender.
Another kamikaze threat neutralised by the US seizure of the Kerama-retto was that of so-called 'suicide boats': on the captured islands more than 250 small motor boats were discovered in heavily camouflaged caves and hangars. These craft were 18 ft (5.5 m) long and carried a single pilot and two 250-lb (113-kg) depth charges. The charges could be dropped next to an Allied ship and would take long enough to sink that the motor boat might theoretically make its escape, so the mission was not strictly a suicide mission, however remote the chances of survival. An attack on the net tender Terebinth on 28 March was made by a boat whose pilot dropped the charges 50 ft (15 m) from his target, inflicting damage on neither, and six more boats were destroyed by gunfire over the next two days. A boat battalion commander was captured and gave the US interrogators a chart of the Japanese plans to attack any landing force off Okinawa with the boats.
As noted above, on 26 March the Deyo’s Gunfire and Covering Support Group (TF54) began the primary gunfire bombardment of Okinawa with six groups of warships: Group 1 comprised the battleships Texas and Maryland, the heavy cruiser Tuscaloosa, and the destroyers Laws, Longshaw, Morrison and Prichett of Destroyer Division 110; Group 2 comprised the battleships Arkansas and Colorado, the heavy cruisers San Francisco and Minneapolis, and the destroyers Hall, Halligan, Paul Hamilton, Laffey and Twiggs of Destroyer Division 51; Group 3 comprised the battleships Tennessee and Nevada, the heavy cruiser Wichita, the light cruiser Birmingham and the destroyers Mannert L. Abele, Zellars, Bryant, Barton and O’Brien of Destroyer Squadron 60; Group 4 comprised the battleships Idaho and West Virginia, the heavy cruisers Pensacola and Portland, the light cruiser Biloxi, and the destroyers Porterfield, Callaghan, Irwin, Cassin Young and Preston of Destroyer Squadron 55; Group 5 comprised the battleships New Mexico and New York, the heavy cruisers Indianapolis and Salt Lake City, and the destroyers Newcomb, Heywood L. Edwards, Leutze, Richard P. Leary and Bennion of Destroyer Squadron 56; and Group 6 comprised the destroyer escorts Samuel S. Miles, Wesson, Foreman, Whitehurst, England, Witter, Bowers and Willmarth. There were also 53 rocket-launching support landing craft.
On 25 March Imperial General Headquarters ordered the start of the 'Ten' plan for the defence of Okinawa and southern Japan, and Vice Admiral Kinpei Teraoka’s 3rd Air Fleet and Vice Admiral Minoru Maeda’s 10th Air Fleet were both placed under the operational command of Ugaki’s 5th Air Fleet based on Kyushu. The remnants of Vice Admiral Takijiro Onishi’s 1st Air Fleet remained on Formosan bases. The Japanese, who were expecting a landing on Okinawa or Formosa at any time, alerted their air forces for 'Ten' on 25 March, but on 27 and 31 March very attacks by B-29 bombers on the airfields effectively shut them down. The Japanese managed to launch only 52 aircraft attacks before the start of 'Iceberg', damaging eight US ships, and 'Ten' could not be started in the full manner envisaged until 6 April, five days after the main landing of 'Iceberg'.
At dawn on 25 March the first kamikaze attack was made by 25 aircraft, of which three returned. The destroyer Kimberly, minelayer Robert H. Smith and fast transports Gilmer and Knudsen were damaged in this attack. During the evening of 26 March there developed an attack by 11 kamikaze aircraft, which scored hits on the battleship Nevada, light cruiser Biloxi, destroyers O’Brien, Porterfield and Callaghan, destroyer escort Foreman and minesweeper Skirmish. The destroyer Halligan was deliberately run aground after receiving a torpedo hit, possibly from the submarine Ro-49. Of TG58.1’s ships, the destroyer Murray was dive-bombed and hit.
On 27 March TF54 continued its gunfire bombardment of Okinawa, and there was an attack by 15 kamikaze aircraft in which the minelayer Adams and minesweeper Southard were damaged.
On 28 March the gunfire bombardment was renewed, the minesweeper Skylark was sunk, and the attack cargo ship Wyandot was damaged by bomb hits. During the night of 28/29 March there were individual attacks by aircraft from Okinawa, and LSM(R)-188 was severely damaged.
As a result the Japanese airfields were bombarded on 29 March and TF52 made attacks on airfields and the bases used for explosive boats and midget submarines.
On 29 March Mitscher positioned his TF58 some 120 miles (195 km) to the south of Kyushu to launch fighter sweeps against Japanese airfields and provide combat air patrol for the invasion forces gathering around Okinawa.
On 30 March there was a preliminary landing of 155-mm (6.1-in) heavy artillery of the XXIV Corps on the Keise-shima, a group of four islets 7 miles (11.25 km) to the west-north-west of Naha, from which the artillery could help provide fire support for the main landings. There was no significant opposition.
Also on 30 March, the escort carriers launched a large raid against Unten-ko, a small cove on the east coast of the Motobu peninsula, where photo-reconnaissance photographs had allowed the detection of a nest of midget submarines. Meanwhile the underwater demolition teams began the task of demolishing beach obstacles, which consisted mostly of wooden anti-boat stakes.
On 30 March, after further shelling of Okinawa, four kamikaze aircraft made an attack during the evening: in which in the attack that the heavy cruiser Indianapolis, flagship of the 5th Fleet, was hit, and Spruance transferred his flag to the battleship New Mexico.
On 31 March there were more kamikaze attacks in which the minelayer Adams, attack transport Hinsdale, and LST-724 and LST-884 were hit, and the Gunfire and Covering Support Group continued its pre-landing bombardment with its 10 battleships, 11 cruisers, 30 destroyers, and 177 gunboats in the final stage of the massive pre-invasion gunfire bombardment, which complemented the air attacks delivered by the warplanes of the Fast Carrier Task Force. These had little effect, although the few remaining Japanese aircraft on the island were destroyed, as the Japanese had pulled back from the beaches and largely refused to respond to attacks from their underground shelters.
The 7th, 77th, and 96th Divisions trained and rehearsed their landings on Leyte island in the Philippine islands group, while the 27th Division staged out of Espíritu Santo in the New Hebrides islands group. The 1st, 2nd and 6th Marine Divisions were located respectively on Pavuvu island in the Solomon islands group, Saipan island in the Mariana islands group and Guadalcanal island in the Solomon islands group. The 1st and 6th Marine Divisions of the III Amphibious Corps rendezvoused at Ulithi atoll in the Caroline islands group and departed for Okinawa late in March, and the 2nd Marine Division departed from Guadalcanal island.
The XXIV Corps and most of its US Army divisions departed from Leyte island just before this, and the 27th Division departed Espíritu Santo island. The other elements of the 10th Army and Island Command left Oahu island in the Hawaiian islands group even earlier.
The amphibious forces encountered rough weather en route, and many groups only just made their target date.
The Japanese had anticipated the landings on Okinawa, which was part of their inner defence zone defined in the 'Outline of Army and Navy Operations' promulgated on 20 January 1945. Beside Okinawa, the major strongpoints in this zone were Iwo Jima, Formosa, Shanghai and southern Korea.
Before the neutralisation of the base at Truk atoll in 'Hailstone' during February 1944, the Okinawa-gunto had been only very lightly defended, but after this the increasing likelihood of a US assault led to a major upgrading of the island’s defensive capability. Thus the 32nd Army had been organised in April 1944 under the command of Lieutenant General Mitsuru Ushijima, who was directly responsible to General Rikichi Ando, the commander of the 10th Area Army on Formosa. The first of the 32nd Army's combat formations to reach Okinawa was Lieutenant General Mamoro Hara’s (from 7 April 1945 Lieutenant General Yasohachi Tasaka’s) 9th Division (7th, 19th and 35th Regiments plus the 9th Artillery Group) from Manchukuo in June 1944, but this division was then relocated to Formosa in December 1944. Late in June, a mere 600 survivors of Major General Shigeji Suzuki’s 44th Independent Mixed Brigade arrived on the island, the other 5,000 men having been lost when the ships convoying them had been sunk by US submarines. The 15th Independent Regiment was delivered by air during July within the context of Japan’s first attempt to airlift so large a force. The 44th Independent Mixed Brigade was rebuilt with the regimental-sized 2nd Infantry Unit and the 15th Independent Regiment. Lieutenant General Tatsumi Amamiya’s 24th Division (22nd, 32nd and 89th Regiments plus the 42nd Artillery Regiment) followed from Manchukuo. Lieutenant General Takeo Fujioka’s 62nd Division (63rd Brigade and 64th Brigade) arrived from China during August.
Much of the Japanese artillery intended for the Philippine islands group in fact remained on Okinawa, and some 3,200 experienced gunners were organised into the 5th Artillery Group. As a result, the US forces on Okinawa were targeted by the largest concentration of Japanese artillery of the Pacific war. These non-divisional artillery units of the 5th Artillery Group and included the Japanese navy’s coast-defence guns, and the 21st Anti-Aircraft Artillery Group controlled the army’s air defences.
In June 1944 the Labour Unit was established as a Boeitai (home guard) force ith about 16,600 Okinawans augmenting regular units, and up to 39,000 Boeitai were conscripted. A further manpower pool was tapped in January 1945 when the 32nd Army directed that all fit male islanders between the ages of 17 and 45 could be mobilised as labour. This total included thousands more on the other islands of the Nansai-shoto (all the island groups between Kyushu and Formosa), and many thousands of these islanders were indeed conscripted.
The strength of the Japanese army on Okinawa at this time was 67,000 including about 5,000 Okinawan conscripts assigned to regular Japanese units. More than 12,000 Korean labourers and comfort women were also present. In March 1945 some 18,500 service troops were reorganised into extemporised, poorly trained and poorly armed 'specially established' infantry regiments and attached to the combat formations.
Some 3,825 Japanese navy personnel and more than 6,000 civilian combatant employees were assigned to Rear Admiral Yoshiaki Ito’s Okinawa Naval Base Force's coast-defence gun, anti-aircraft, air service and construction units, all assigned to the defence of the Oroku peninsula in the south of Okinawa. The Japanese forces on the islands were also combed for non-essential personnel, who were then grouped in two special infantry brigades (one of 6,000 men and the other of 4,500 men) and one special regiment (3,000 men).
Ushijima also reduced the sea raiding battalions to one company each, the surplus manpower being used to create three 800-man infantry battalions. The 32nd Army had been promised another division from the home islands, but this did not arrive. The Japanese thus possessed the military resources to defend only about one-third of the island of Okinawa.
By this time a new Japanese tactical doctrine of shugettsu (bleeding strategy), which had first been deliberately applied on Iwo Jima against 'Detachment', had been adopted. This acknowledged that the Japanese forces had no realistic hope of repelling an invasion on the beaches as the assault forces came ashore, and was therefore posited on inflicting on the Americans, whom the Japanese knew to be highly averse to suffering casualties, losses so great that they would hesitate to invade the home islands. In August 1944 the Japanese army had released the 'Essentials of Island Defences' tactical manual, which emphasised the desirability of a mobile defence anchored at strongpoints and the implementation of local counterattacks. Other factors which were emphasised dispersal and concealment, while beach defence was de-emphasised in acceptance of the massive volume and weight of the fire support with US assault forces would receive.
In accordance with this doctrine, Ushijima deployed only two battalions in the northern two-thirds of the island. However, the shugettsu concept flew in the face of a generation of Japanese training, which emphasised offensive operations, and even the Emperor Hirohito questioned why the airfields on Okinawa had been given up so easily. As it was, the 10th Area Army would order a counterattack to retake the airfields, which were desired for kamikaze operations, but Ushijima ignored this instruction.
The Japanese therefore decided not to attempt a defence of the central plain and, with it, the airfields at Yontan and Kadena, on the grounds that the airfields could not be used once the US forces had arrived and that the 32nd Army would be quickly destroyed on the exposed plains. Moving this army to the rugged north might prolong its survival, but this option would deprive it of the resources available in the south, and prevent it from compelling the US forces into close combat and inflicting unacceptable losses on them.
The 32nd Army's deployment therefore located the 62nd Division to cover an area in the south from Naha and Shuri north to a line anchored on the eastern and western coasts on the second narrowest neck of the island, the Chan isthmus, some 3.5 miles (5.6 km) wide, between Nakagusuku Bay in the east and Hagushi Bay in the west. Under the command of Ushijima, Lieutenant General Isamu Cho (32nd Army chief-of-staff, who wanted an offensive strategy) and Colonel Hiromichi Yahara (32nd Army chief of operations, who wanted a defensive strategy), this north-facing front was dug in on some of the first high ground encountered to the south of the central plain where it was believed the US forces would land. A more formidable defence line behind this was centred on the rugged Urasoe-Mura escarpment, Tanabaru escarpment and several ridges running 2.55 miles (4.1 km) from north-west to south-east across the island.
The main defence line was still farther to the south, however, and was centred on the Shuri Castle and a vast, rugged cross-island ridge-and-hill complex. Forces on this line were withheld from the first weeks of the fighting, so that the US forces, tired and degraded after considerable earlier combat, would then find themselves faced by well prepared and formidable defences held by fresh Japanese troops.
The 24th Division secured the southern end of the island to prevent landings and act as the 32nd Army's reserve. The 44th Independent Mixed Brigade was deployed to the south-east of the 62nd Division for the defence of the Chinen peninsula, where it was thought the US forces might land on the island’s south-eastern Minatoga beaches.
Rear Admiral Minoru Ota’s Okinawa Auxiliary Naval Base Force (3,825 naval personnel and more than 6,000 conscripted civilians) secured the Oroku peninsula to the south-west of the 62nd Division with orders to fight the US forces on the water’s edge in accordance with standard Japanese navy tactical doctrine. The island’s northern part was not completely abandoned. The 1st Specially Established Regiment (created from airfield service personnel) screened the Yontan and Kadena airfields on the central plain. The regimental-sized 2nd Infantry Unit, detached from the 44th Independent Mixed Brigade, was established on the Motobu peninsula on the island’s north-western coast to distract and divert part of the US forces. One of its elements, the 2,000-man 'Igawa' Unit, was located on Ie-shima, a small island just to the west of the Motobu peninsula, together with other small elements to hold the airfields.
Thousands of pillboxes, bunkers, weapons emplacements, and fighting positions were dug. Terrain features were incorporated into the defence and weapons were well sited with excellent overlapping fields of fire. Anchored on dominating terrain features, multiple defence lines were established across the island, and the construction and improvement of these repeating lines in fact continued through the battle as the Japanese were driven south. Supplies and munitions were protected in dug-outs and caves. Extensive tunnel systems were dug, with a length of some 60 miles (100 km), sufficient to protect the Japanese army’s 100,000 troops.
Another formation under 32nd Army command was Lieutenant General Toshiro Nomi’s 28th Division, which was garrisoning the Sakishima-gunto. Thus the defence of Okinawa proper was entrusted to the 24th Division and 62nd Division and the 44th Independent Mixed Brigade, supported by the 5th Artillery Group, one divisional field regiment of artillery, and Lieutenant Colonel Murakami’s 27th Tank Regiment. The Japanese defence was led in the south by Ushijima (24th Division behind the left flank of the Shuri Line and the 44th Independent Mixed Brigade behind the line’s right flank between Naha and Yonabaru), and in the north by Lieutenant General Takehido Udo (62nd Division disposed in the neck of the island between Chatan and Toguchi).
The garrison also included seven sea raiding battalions with 'Shinyo' type suicide attack boats (three in the Kerama-retto and the other four on Okinawa).
As noted above, the main components of Turner’s TF51 (Joint Expeditionary Force) were Deyo’s Gunfire and Covering Support Group (TF54) of 10 battleships, 11 cruisers and 30 destroyers, and Blandy’s Amphibious Support Force (TF52) of 22 escort carriers of which four carried Marine Aircraft Groups 31 and 33. TF51 was entrusted with the delivery of the Expeditionary Troops in some 1,139 transports, landing craft and auxiliaries. Spruance had at his disposal more than 300 warships including Mitscher’s TF58 (four fast carrier task groups comprising 11 fleet carriers, six light carriers, seven battleships, 18 cruisers and 64 destroyers) and the British TF57 (one fast carrier task group comprising four fleet carriers, two battleships, five cruisers and 11 destroyers) to soften up and then neutralise as much as possible of the island’s defences before the landings were committed, and then to ward off any Japanese naval counter-offensive, however unlikely this latter might be given the virtually complete destruction of Japan’s surface fleet by this time.
Although the land battle was entirely a US campaign, Allied warships added to the air bombardment principally supplied by TF57 carrier group with British, Australian and New Zealand ships and personnel providing about 20% of the available naval air power. TF57 was assigned the task of neutralising the Japanese airfields in the Sakashima-gunto, which it did from 26 March until 10 April in 'Iceberg I'. On 10 April, its attentions were transferred to airfields on northern Formosa in 'Iceberg Oolong'. The force withdrew to San Pedro Bay in the Philippine islands on 23 April, returning to action on 4 May and setting about the airfield-reduction role as before, but this time with naval gunfire as well as air attack. A number of kamikaze attacks caused significant damage but only a brief interruption to the operations of TF57, which withdrew to Guam and Manus island on 25 May.
The 10th Army was in itself a new formation, but its component parts were for the most part veterans of other Pacific operations. In the XXIV Corps (Southern Attack Force), the 7th Division had seen action on Attu, Kwajalein and Leyte, and the 96th Division on Leyte, while in the III Amphibious Corps (Northern Attack Force) the 1st Marine Division had seen action on Guadalcanal, New Britain and Peleliu, and 6th Marine Division on the Marshall islands, Guam and Saipan. The 10th Army’s reserves were the 27th Division (operational experience in the Gilbert islands group, the Marshall islands croup and Saipan), 77th Division (operational experience on Guam and Leyte) and 2nd Marine Division (operational experience on Guadalcanal, Tarawa, Saipan and Tinian). Buckner thus had some 182,800 men in seven divisions, of whom 116,000 were to be committed in the initial phase.
Before considering the assault itself, it is worth looking at a few related incidents. The US Navy’s submarine arm had, by a time late 1944, wrought havoc upon Japanese shipping. Among the Japanese losses were the troop ship Toyama Maru, sunk on her way to Okinawa by Sturgeon: this caused a loss of about 5,600 men, but as the sinking occurred nine months before the land campaign, these Japanese deaths are usually not figured in accounts of the battle losses. Before the battle the evacuation ship Tsushima Maru was sunk by Bowfin and 1,484 women and children died. On 10 October 1944 the virtually defenceless Okinawa was pummelled by waves of US bombers: more than 80% of Naha, the island’s capital, were destroyed, and more than 65 vessels were sunk. Shortly after the start of the battle, the Japanese battleship Yamato was sunk by US Navy aircraft on her trip to Okinawa in the disastrous 'Kikusui-1' operation. The Japanese had planned to beach Yamato on Okinawa’s shore, and to use her as a land battery.
'Iceberg' was based on transport by Turner’s TF51, with 1,213 vessels including 603 landing craft, of Buckner’s 10th Army and then the landing of this army on Okinawa: 451,866 men, including three reserve divisions, were embarked.
The Northern Attack Force (Reifsnider’s TF53 with the headquarters ship Panamint) landed Geiger’s III Amphibious Corps: within this, Commodore H. B. Knowles’s TG 53.1 (Transport Group Able) transported and landed Shepherd’s 6th Marine Division in 16 attack transports, six attack cargo ships, one dock landing ship and the vehicle landing ship Catskill, and Commodore Moyer’s TG53.2 (Transport Group Baker) transported and landed del Valle’s 1st Marine Division in 15 attack transports, six attack cargo ships, two dock landing ship and the vehicle landing ship Monitor.
Divided between both marine divisions there were also 46 tank landing ships, five medium landing ships and 16 tank landing craft as well as 18 leader vessels (PCSs, patrol craft and submarine chasers). Their escort was provided by TG53.6 (Northern Attack Force Screen) with the destroyers Morris, Mustin, Lang, Stack and Sterett of Destroyer Division 4 and Pringle, Hutchins, Massey, Russell, Wilson, Stanly, Howorth and Hugh W. Hadley of Destroyer Division 90, the destroyer escorts Gendreau, Fieberling, William C. Cole, Paul G. Baker and Bebas, the troop-carrying destroyer conversions Charles Lawrence and Roper, two PCE escort vessels and one submarine chaser.
The Southern Attack Force (Hall’s TF55 with the headquarters ship Teton) landed Hodge’s XXIV Corps: within this, Commodore M. O. Carlson’s TG55.1 (Transport Group Dog) transported and landed Arnold’s 7th Division in 16 attack transports, seven attack cargo ships, one dock landing ship and the vehicle landing ship Ozark and, in addition, 30 tank landing ships, 22 medium landing ships and two infantry landing craft, and Commodore C. G. Richardson’s TG55.2 (Transport Group Easy) transported and landed Bradley’s 96th Division in 16 attack transports, six attack cargo ships, two dock landing ships, 23 tank landing ships, five medium landing ships, one infantry landing craft and six support support landing craft. Nineteen leader vessels and 17 more support landing craft were allocated, and escort was provided by TG55.6 (Southern Attack Force Screen) with the destroyers Anthony, Bache and Bush of Destroyer Division 48, Bennett, Hudson, Hyman, Purdy, Beale, Wadsworth and Ammen of Destroyer Squadron 45, and Putnam and Rooks of Destroyer Squadron 66, the destroyer escorts Crouter, Carlson, Damon M. Cummings, Vammen, O’Neill and Walter C. Wann, the troop-carrying destroyer conversion Stringham, one PCE escort vessel and two submarine chasers.
Preceded by the 'Juneau' minesweeping operation to clear the approaches, the landing on the western side of the island of Okinawa started at 08.00 on 1 April minesweeping operation to clear the approaches, 'Iceberg' proper had started on an 8-mile (13-km) stretch of beach in Hagushi Bay with the III Amphibious Corps' two divisions in the north (6th Marine Division on the left and 1st Marine Division on the right) the XXIV Corps' two divisions in the south (7th Division on the left and 96th Division on the right), and went according to plan against what was at first only very light resistance. The landed troops were strongly supported by the gunfire of TF54’s battleships, cruisers and destroyers, and the close support of aircraft (totalling 564 at the start of the operation) of TF52’s escort carriers and TF58’s fleet and light carriers, of which two groups remained constantly in the operational area while the third was being replenished.
From 31 March to 2 April the British carriers of Rawlings’s TF57 carried out daily neutralisation raids on the islands of the Sakishima-gunto, and while being replenished between 3 and 5 April were relieved by Sample’s Group 3 escort carriers. During the evening of 1 April the landing fleet and its support forces came under kamikaze attack by aircraft and Okha manned missiles. The battleship West Virginia and the transports Hinsdale and Alpine, as well as LST-884, were hit, and the destroyer Prichett, minesweeper Skirmish and transport Elmore were damaged by bombs from dive-bombers and high-level bombers; the destroyer escort Vammen was also damaged, possibly by an assault boat. The British carrier Indefatigable and destroyer Ulster were hit in kamikaze attacks by the 1st Air Fleet, the destroyer being towed to Leyte by the cruiser Gambia.
In the evening of 2 April 14 aircraft made kamikaze attacks on the transports carrying the embarked 77th Division, and the attack transports Chilton, Henrico, Goodhue, Achernar and Tyrell were badly damaged. The troop-carrying destroyer conversion Dickerson was so severely damaged that she had to be scuttled on 4 April. Bombers hit the destroyer escort Foreman. On 2 April the destroyer Franks was damaged in a collision with battleship New Jersey and the destroyer Boric in a collision with the carrier Essex.
Early on 3 April LST-599 was damaged by a kamikaze aeroplane and at dusk the escort carrier Wake Island, minesweeper Hambleton, destroyer escort Foreman, transport Telfair and LCT-876 suffered in the same way. The destroyer Wilson was later damaged by a kamikaze aeroplane, and Sproston was damaged in a dive-bomber attack.
On 4 April there were heavy storms, and therefore no kamikaze attacks. However, LST-70, LST-624, LST-675, LST-756, LST-1166, LST-689, LST-736, LST-343, LST-570 and LST-781 were damaged on the beaches.
On 5 April the battleship Nevada took five hits from a Japanese coastal battery while shelling shore targets, and the light minelayer Harry F. Bauer was damaged by the impact of a torpedo whose warhead failed to detonate. There were also many collisions, and damage was also caused by the storm.
On 8 April TF58 resumed its support for the Okinawa operations. After the return of TG58.2 from replenishment, TF58 comprised Clark’s TG58.1 with the fleet carriers Hornet and Bennington, light carriers Belleau Wood and San Jacinto, battleships Massachusetts and Indiana, heavy cruiser Vincennes, light cruisers Miami, Vicksburg and San Juan, and destroyers of Destroyer Squadrons 25 and 61; Bogan’s TG58.2 with the fleet carriers Randolph and Enterprise, light carrier Independence, battleships Washington and North Carolina, heavy cruisers Baltimore and Pittsburgh, light cruisers Flint and Oakland, and destroyers of Destroyer Squadrons 52 and 53; Sherman’s TG58.3 with the fleet carriers Essex and Bunker Hill, light carrier Bataan, battleships New Jersey and South Dakota, light cruisers Pasadena, Springfield, Astoria and Wilkes-Barre, and destroyers of Destroyer Squadrons 45, 62 and 48; and Radford’s TG58.4 with the fleet carriers Yorktown and Intrepid, light carrier Langley, battleships Wisconsin and Missouri, super-heavy cruisers Alaska and Guam, light cruiser San Diego and destroyers of Destroyer Squadrons 47 and 54.
At least two of these task groups were in the operational area every day, with one group replenishing and the other either arriving or withdrawing.
While the British TF57 was replenishing on 8 and 9 April, Sample’s escort carrier group (Suwanee, Chenango, Santee and Rudyerd Bay) assumed the task of neutralising the Sakishima-gunto islands. From 11 to 13 April TF57, now reinforced with the cruisers Uganda and Gambia and the destroyers Ursa, Urchin and Whirlwind, made daily attacks on the airfields and installations in northern Formosa. On 14 and 15 April TF57 replenished once again, and the carrier Formidable relieved Illustrious while the destroyers Kempenfelt and Wessex replaced Urania and Quality.
During this period Sample’s force continued its operations against the Sakishima-gunto.
Meanwhile, as the main landings were being carried out, the 2nd Marine Division made a demonstration on the eastern side of the island as a diversionary feint, though the 10th Army’s contingency plans envisaged that this diversion could be turned into a real landing in Nakagusuka Bay to link with the main landings should Japanese resistance behind Hagushi Bay prove to be stronger than anticipated. In the event the eastern landing was not required, for the main assault went as planned, and by 4 April the marine forces of the III Amphibious Corps had advanced north to the Ishikawa isthmus just to the south of Onna, while the army troops of the XXIV Corps had pushed to the south as far as Kuba, so dividing the Japanese defence into portions in the north and extreme south of the island.
Thus the 10th Army had swept across the south-central part of the island of Okinawa with what was, by the standards of World War II, relative ease, in the process capturing the Kadena and Yontan air bases within hours of the landing. In light of the weak nature of the Japanese opposition, Buckner decided to proceed immediately with the second phase of his plan, namely the seizure of northern Okinawa. The 6th Marine Division headed to the north along the Ishikawa Isthmus and by 7 April had sealed off the Motobu peninsula, and by 11 April the marines had reached a line between Tako on the west coast and Taira on the east coast.
Two days later, on 13 April, the 2/22nd Marine Regiment reached Hedo Point at the northernmost tip of the island. By this date the bulk of the Japanese forces in the north, the 2,000-man 'Udo' Force, was cornered on the Motobu peninsula. Here, the terrain was mountainous and wooded, and the Japanese defences were concentrated on the Yae-dake hill complex, which was a twisted mass of rocky ridges and ravines in the centre of the peninsula. There was heavy fighting before the marines finally cleared Yae-dake on 18 April, though the last elements of the Japanese resistance were not destroyed until 1 May. The last stage in the clearance of northern Okinawa was completed on 19 April as marines moving to the south along the east coast from Hedo Point reached Aha and met other marines moving to the north along the same side of the island from Taira.
On 10/11 April a battalion of the 105th Infantry of the 27th Division took the islet of Tsugen-shima to the south-east of the Katchin peninsula: casualties were 24 Americans killed and 100 wounded, while the Japanese lost about 280 troops. The Katchin peninsula and the rest of the coast of Chimu Bay and the east coast of Okinawa to the north, was the objective of the 1st Marine Division. Tsugen-shima commanded the approaches to Nakagusuku Bay, which could have been used for another landing if such had been required.
Meanwhile, at 07.58 on 16 April elements of the 77th Division assaulted Ie-shima, a small island off the western end of the Motobu peninsula dominated by the 607-ft (185-m) height of the Iegusuga volcano, with landings on its south and west coasts. In addition to the conventional hazards of infantry operations in close terrain, the 77th Division encountered kamikaze attacks and even local women armed with spears. There was heavy fighting before Ie-shima was declared secured on 21 April and became another air base for operations against the Japanese forces. The seizure of this small island cost the Americans 172 men killed and 902 wounded.
The primary gains of this rapid seizure of the north was the fact that the airfields at Kadena and Yontan could quickly be brought back into service as the homes of US tactical warplanes supporting their forces fighting in the south.
On 8 April, following the sinking of the super-battleship Yamato at the end of 'Kikusai-1', Turner reported to Nimitz that 'I may be crazy but it looks like the Japs have quit the war, at least in this section.' This was just a single reflection among many indicating a wholly over-inflated US sense of unrealistic optimism. Nimitz was more sanguine, and signalled back 'Delete all after 'crazy!' Nevertheless, while the 27th Division was ashore by 10 April, Turner ordered the 2nd Marine Division back to Guam to relieve shipping congestion.
As events were soon to reveal, the Japanese defences in the south were an altogether tougher nut for the XXIV Corps to crack, for here Ushijima had prepared the Machinato Line outer defences and the immensely strong Shuri Line main defences just to the north of Naha. Thus the Japanese resistance stiffened as the US forces moved to the south, and XXIV Corps soon encountered deeply entrenched Japanese troops in the coral ridges dominating the southern half of the island. These ridges extended right across the island and restricted fields of fire, reducing the US superiority in firepower. The Japanese strongpoints included pillboxes with steel doors, and these proved highly resistant to the effects of the flamethrower, which was the weapon generally used in the reduction of Japanese fortifications. The Japanese also sometimes took cover in the numerous stone tombs peculiar to the indigenous Okinawan culture. The campaign therefore degenerated into static warfare in some ways comparable to that of World War I. A notable feature of the battle was that, for once, the Japanese had ample fire support, as suggested by the fact that the Japanese artillery on one occasion fired 14,000 shells on XXIV Corps in a single 24-hour period.
Buckner was now faced with the dilemma of undertaking a costly frontal assault or chancing the danger of dividing his forces to launch an amphibious assault in the rear of the Shuri Line. Buckner opted for both, though emphasis in the shorter term was given to a frontal assault after a Japanese suicide attack on 3 May revealed the main features of the Shuri Line.
Even as the 6th Marine Division cleared the northern two-thirds of Okinawa, the US Army’s 96th Division on the right and 7th Division on the left wheeled to the south across the narrow waist of Okinawa. The 96th Division began to encounter fierce resistance in west-central Okinawa from Japanese troops holding fortified positions to the east of Highway No. 1 and about 5 miles (8 km) to the north-west of Shuri, from what came to be known as Cactus Ridge. The 7th Infantry Division encountered similarly fierce Japanese opposition from a rocky pinnacle located about 1,000 yards (915 m) to the south-west of Arakachi and later dubbed 'The Pinnacle'. By the night of 8 April, US Army forces had cleared these and several other strongly fortified positions, in the process suffering more than 1,500 casualties but killing or capturing about 4,500 Japanese. What was not yet fully appreciated by the Americans was the fact that the main battle had only just begun, for what they had succeeded in taking were merely outposts guarding the approaches to the Shuri Line.
The next US objective was Kakazu Ridge, comprising two hills with a connecting saddle which constituted part of the Shuri Line’s outer defences. The Japanese had prepared their positions well and fought tenaciously, often from fortified caves. On many occasions the US forces suffered moderately severe casualties before they could clear the Japanese from each cave or other hiding place. The Japanese sent Okinawans at gunpoint out to acquire water and supplies for them, and this led inevitably to civilian casualties. The US advance was inexorable but resulted in a high number of casualties on both sides.
As the US assault against Kakazu Ridge stalled, at the urging of Cho, Ushijima decided to take the offensive. On the evening of 12 April, the 32nd Army attacked US positions across the entire front. The Japanese attack was well conceived and heavy, and was pressed with determination. The assault achieved a modest penetration of the US lines, but the three battalions which had achieved this penetration were then cut to ribbons, two being wiped out and only half the men from the third making it back to the Japanese lines. The Japanese repeated their offensive on the following night, and a final assault on 14 April was again repulsed. The effort led the 32nd Army's staff to conclude that the US forces were vulnerable to night infiltration tactics, but that their superior firepower made any offensive Japanese troop concentrations extremely dangerous, and they reverted to their defensive strategy.
Landed on 9 April, the 27th Division took over on the right, along the west coast, and Hodge thus three divisions in the line: the 27th Division on the right, the 96th Division in the centre and the 7th Division on the left, each division holding about 1.5 miles (2.4 km) of the front. Hodge launched a new three-division offensive on 19 April. The attack was preceded by a massive bombardment, the heaviest of the entire Pacific campaign, in which 19,000 rounds were fired by the 324 guns of 27 artillery battalions. Battleships, cruisers and destroyers joined the bombardment, and the bombardment was followed by the attacks of 650 US Navy and US Marine Corps warplanes, which targeted the Japanese positions with napalm, rockets, bombs, and machine guns. The Japanese defences were sited on reverse slopes, however, and here the defenders waited out the artillery barrage and aerial attack in comparative safety, emerging from the caves to rain mortar rounds and grenades upon the Americans advancing up the forward slope. Thus the US attack was halted in its tracks by Japanese defenders whose deep fortifications had remained largely undamaged.
By 23 April, however, Ushijima had ordered a withdrawal from the forward positions to the strongest part of the defence line, centred on Shuri Castle. The withdrawal was covered by fog and artillery and was not detected by the Americans until the next morning.
A tank assault to achieve a breakthrough, by outflanking Kakazu Ridge, failed to link with its supporting infantry attempting to cross the ridge, and failed with the loss of 22 tanks. Although flamethrowing tanks cleared many cave defences, there was no breakthrough, and the XXIV Corps lost 720 men killed, missing and wounded. These losses could well have been more substantial but for the fact that the Japanese had practically all of their infantry reserves tied up farther to the south, held there by another feint off the Minatoga beaches by the 2nd Marine Division coinciding with the attack.
At the end of April, after the US Army forces had pushed through the Machinato Line, the 1st Marine Division relieved the 27th Division, and the 77th Division relieved the 7th Division. When the 6th Marine Division arrived, Geiger’s III Amphibious Corps took over the right flank of the offensive to the south, and the 10th Army assumed control of the battle from the XXIV Corps.
On 4 May, the 32nd Army launched its second counter-offensive, and on this occasion Ushijima attempted to support the main land attack with amphibious assaults on the coasts behind the US lines. To support this offensive, the Japanese artillery moved into the open, and was able to fire 13,000 rounds in support, but effective US counter-battery fire destroyed dozens of Japanese pieces of artillery.
This second Japanese counter-offensive was undertaken on a major scale with the best troops of all three divisions and timed to coincide with the 'Kikusui-5' operation. The Japanese effort was launched at dawn with the support of the most massive artillery barrage by the Japanese in the Pacific war, and was preceded by night counter landings behind both US coast flanks. However, the western counter-landing force became disoriented in the darkness and came ashore too far to the south, running directly into the US Marine line instead of behind it, and was annihilated with the help of LVT(A)s. The eastern force was sighted by warships and driven back into the sea by the reconnaissance element of the 7th Division. The main attack fared no better. Only a single battalion broke through the US front, and the offensive was called off after 1.5 days, by which time the Japanese had suffered some 7,000 men killed. Four days later the Americans fired a massive barrage on the Japanese positions as a celebration of the surrender of Germany.
The low point of the campaign was reached with torrential rains that began on 16 May. These continued with little pause until the end of the month, and greatly increased the misery of the troops on the ground.
The US forces might never have secured the island had it not been for the lack of cohesion among the Japanese defenders. Many officers were unhappy with the shugettsu concept and insisted on making local counterattacks whose sole result was to offer targets for destruction by the Americans' massively superior firepower. Most the Japanese formations had been pieced together from disparate units, and battalion commanders revealed a tendency not to tie their defences into those of neighbouring battalions and, as a result, the Americans became increasingly adept at infiltrating the Japanese lines at unit boundaries. For the first time in the Pacific war, the Japanese were forced to feed replacements directly into the line, and observers on both sides noted that the Japanese infantry became increasingly reluctant to reveal their positions by firing in support of neighbouring positions manned by soldiers they hardly knew.
Buckner launched another US attack on 11 May, and there followed 10 days of fierce fighting. On 13 May men of the 96th Division and 763rd Tank Battalion captured Conical Hill. Rising 476 ft (145 m) above the Yonabaru coastal plain, this feature was the eastern anchor of the main Japanese defences and was defended by about 1,000 Japanese. Meanwhile, on the opposite coast, the 1st and 6th Marine Divisions fought for Sugar Loaf Hill. The capture of these two key positions exposed the Japanese around Shuri on both flanks, and Buckner now hoped to be able to envelop Shuri and trap the main body of the Japanese defenders.
By the end of May, monsoon rains had turned contested hills and roads into deep and cloying morasses who existence exacerbated both the tactical and medical situations. The ground advance came more and more to resemble those typical of many World War I battlefields as troops became mired in mud and flooded roads greatly inhibited evacuation of wounded to the rear. Troops lived on a field sodden by rain, part garbage dump and part graveyard. Unburied Japanese and US bodies decayed, sank in the mud, and became part of a noxious mess of mud and decay. Any man unfortunate enough to slide down the greasy slopes could easily find their pockets full of maggots at the end of the journey.
The Japanese line finally began to crack in late May. On 27 May Naha fell, and two days later del Valle, the commander of the 1st Marine Division, ordered Company A of the 1/5th Marines to capture Shuri Castle. The loss of the castle was a massive psychological blow to the Japanese, and also represented a strategic milestone inasmuch as it precipitated the collapse of the Shuri Line defences. Shuri Castle had been shelled by the battleship Mississippi for three days before the start of this advance, and the weight of the bombardment had led the 32nd Army to withdraw to the south, and the marines therefore had an easy task in securing Shuri Castle. The castle lay outside the 1st Marine Division’s assigned zone, however, and only frantic efforts by the commander and staff of the 77th Division prevented a US air attack and artillery bombardment which would have resulted in many 'friendly fire' casualties.
Harassed by artillery fire, the Japanese retreat to the mountainous region in the extreme south of the island nearly turned into a rout, with many wounded men simply abandoned and, for the first time in the Pacific war, large numbers of men deserting, but was then taken in hand and completed with great skill at night and with the aid of monsoon storms. The 32nd Army was able to move nearly 30,000 men into its last defence line on the Kiyan peninsula. The Japanese were steadily compressed deeper into this small pocket on the south-western corner of the island, which was savaged by US fire which became increasingly concentrated as the pocket shrank. Large numbers of Okinawan civilians, terrified of falling into American hands, were caught up in the retreat and experienced terrible hardships, many thousands of them dying.
Away to the north-west there were about 9,000 Japanese naval troops, supported by 1,100 militia, with about 4,000 of these holed up in the underground headquarters on the hillside overlooking the Okinawa naval base on the Oroku peninsula, to the east of the airfield, after Ota had refused Ushijima’s order to abandon the Oroku peninsula. On June 4, elements of the 6th Marine Division launched an amphibious assault on the peninsula. The 4,000 Japanese naval personnel, including Ota, committed suicide within the hand-hewn tunnels of the underground naval headquarters after the marines had taken Admiral’s Hill, the main Japanese position, on 13 June.
By 17 June, the remnants of Ushijima’s shattered 32nd Army had been driven into a small pocket in the far south of the island round Kiyamu to the south of Itoman. On 18 June Buckner was killed by Japanese artillery fire while monitoring the forward progress of his troop, and was succeeded as an interim measure by Geiger who, on assuming command, became the only US Marine to command a numbered army of the US Army in combat. Geiger passed command five days later to Lieutenant General Joseph W. Stilwell.
The last organised remnants of Japanese resistance succumbed during the night of 21/22 June, although some Japanese decided instead to hide. Ushijima and Cho committed suicide at 03.00 on 22 June in their command headquarters on Hill 89 in the closing hours of the battle. Yahara had asked Ushijima for permission to commit suicide, but the general refused his request on the grounds that 'If you die there will be no one left who knows the truth about the battle of Okinawa. Bear the temporary shame but endure it. This is an order from your army commander. Yahara was thus the most senior officer to survive the battle on the island.
The official surrender ceremony was held on 7 September near Kadena airfield.
Buckner was widely criticised for failing to use his own artillery effectively, and also for rejecting proposals for a second amphibious landing in the Japanese rear, at Nakagasuku Bay, by his afloat reserve, the 2nd Marine Division.
The whole campaign had been one of appalling severity, costing the Japanese 107,500 known dead and possibly another 20,000 dead in caves sealed by US assault teams armed with flamethrowers and explosives. Large numbers of civilians were killed or committed suicide, but for the first time in the war with Japan an appreciable number of service personnel surrendered: these totalled some 7,455 (including 2,300 Japanese) mostly during the very last few days of the campaign as the 32nd Army was disintegrating as a cohesive fighting formation.
The US losses amounted to 7,613 dead and 31,800 wounded in the 10th Army, which also suffered 33,096 non-combat wounded. The US Navy lost 4,900 dead and another 4,800 wounded as its ships had come under exceptionally heavy kamikaze air attack during the campaign, losing 38 of their number sunk and another 368 damaged. The US Navy and US Marine Corps personnel losses were in the order of 17% of all these two services' losses in the Pacific war.
US aircraft losses were 763, a large number by any standards, but those of the Japanese were quite staggering at an overall figure of 7,800 including 1,465 in 1,900 kamikaze attacks.
Stilwell declared the Ryukyu islands campaign over on 2 July as the Americans were beginning to realise quite how bloody the whole operation had been. Ushijima’s formidable defensive effort had bought Japan three months, and the question the USA was now asking was the probable cost of the apparently inevitable US invasion of the Japanese home islands given the same type of fanatical resistance. To this extent, therefore, the shugettsu had proved its worth.
Following the end of the battle, the Americans started to develop Okinawa into the major base from which to commit the invasion of the Japanese home islands. Some 87,000 construction troops were brought in and construction of 25 airfields began, though only a few of these had been completed before the surrender of Japan. The completed airfields boasted six 10,000-ft (3050-m) runways.
With the approaches cleared by the capture of Tsugen-shima, work began on transforming Nakagusuku Bay into a forward naval base for the final assault on Japan, with docks and cargo handling facilities. By 1 January 1946, US Navy facilities on the island covered 20,000 acres (8040 hectares).
It should also be added that the mere fact of the Americans successfully coming ashore on Okinawa brought about the fall of the administration of General Kuniaki Koiso, who resigned as Japanese prime minister on 4 April.