This was the US seizure of Cape Gloucester, at the western end of New Britain in the Bismarck islands group, by Major General William H. Rupertus’s 1st Marine Division of General Douglas MacArthur’s South-West Pacific Area command, and otherwise known as 'Operation IIIA', within the 'Dexterity' plan (26 December 1943/22 April 1944).
Cape Gloucester is the western tip of the large island of New Britain. The area is mostly covered with dense jungle, and is characterised by inland mountains and coastal swamps. However, there are scattered areas of grassland inland on the coastal plain suitable for airfield construction. The area is dominated by Mt Talawe, which rises to a height of of about 5,825 ft (1775 m). The area had a number of trails used by the local population, but no other infrastructure. The coast on the western side of Borgen Bay to the east of Cape Gloucester had several breaks in the reef opening onto beaches deemed suitable for amphibious landings.
In operational terms, the importance of Cape Gloucester lies in the fact that it commands the Dampier Strait between New Britain and New Guinea.
New Britain had been taken by the Japanese forces of Major General Tomitaro Horii’s South Seas Detachment in the period immediately after 23 January 1942, and had then been developed as the major base area and bastion for the South-East Area command. Rabaul provided an ideal location for the basing of a Japanese fleet, army and navy air formations, and all the command and control centres required to direct, launch and support the conquest of New Guinea and the South Pacific region. This base area was centrally located and, at least initially, sufficiently far from Allied bases to protect it from effective air and sea attack. The northern part of New Britain island possesses one of the best anchorages in the region and provided land suitable for the construction of several airfields. After their occupation of Rabaul, the Japanese therefore began to develop Rabaul into a major base complex, and this was completed in late 1942.
The Japanese did not possess a true joint command as was becoming standard in the Allied forces, but Imperial General Headquarters had directed General Hitoshi Imamura’s 8th Area Army and Vice Admiral Jinichi Kusaka’s South-Eastern Area Fleet, both with their headquarters in Rabaul, to work in concert, and the two commands in fact did so to a degree which was more marked and practical than was evident in comparable arrangement within other theatres. The 8th Area Army controlled Lieutenant General Hatazo Adachi’s 18th Army and Lieutenant General Giichi Itahana’s (from 1 April 1944 Lieutenant General Masazumi Ineda’s) 6th Air Division in the eastern part of New Guinea, Lieutenant General Harukichi Hyakutake’s 17th Army on Bougainville island, and Lieutenant General Sadaaki Kagesa’s 38th Division, Lieutenant General Hidemitsu Nakano’s 51st Division (shipped to New Guinea in March 1943), and Major General Iwao Matsuda’s 65th Independent Infantry Brigade on New Britain island.
The South-Eastern Area Fleet comprised Vice Admiral Baron Tomoshige Samejima’s 8th Fleet based in the Shortland islands group and Vice Admiral Nihizo Tsukuhuru’s 11th Air Fleet based at Rabaul.
With the advantages offered by long-range power projection by land-based bombers a cornerstone of their strategic and operational thinking, the Japanese embarked on a major programme to improve existing airfields and also to build new airfields: the existing Vunakanau and Lakunai airfields were upgraded, the former becoming the main Japanese air base; and other airfields were built at Keravat on Ataliklikun Bay some 6 miles (10 km) to the east of Vunakanau, Rapopo some 13 miles (21 km) to the east of Vunakanau on the north coast of Cape Gazelle, and Tobera some 7 miles (11.25 km) to the south-west of Rapopo. Farther away from Rabaul, but still on New Britain island, two airfields were built at Cape Gloucester, which the Japanese knew as Tuluvu after a village of the area, one at Cape Hoskins on the northern side of the central coast and one Gasmata on the southern side of the central coast. Another small airfield was built on the north coast to the south of Open Bay at Ubili. Thus the Japanese had nine airfields from which their aircraft could operate.
Significant naval base facilities were built at Rabaul, and these included a submarine base on Tallili Bay.
As the Allied forces closed on Rabaul, securing a ring of islands around it to effect its isolation, the Japanese began major preparations for the defence rather than merely the use of this primary base area. With the complete loss of the Solomon islands group and much of the eastern part of New Guinea, the Japanese embarked on preliminary work for the defence of the Dampier and Vitiaz Straits, to the east and south-west of Rooke island in the waters between the western end of New Britain island and the Huon peninsula of North-East New Guinea, during October 1943.
Like most of those in the South-West Pacific Area, the islands of the Bismarck archipelago are of volcanic origin with steep mountain slopes, thick jungle and treacherous marshes in which malaria and a host of other tropical diseases were a problem for all troops deployed in them. The climate is almost permanently hot and humid, seldom ameliorated by the torrential rain and dense cloud which afflict the region.
Up to World War I a German possession, the islands had been administered by Australia under a League of Nations mandate after the end of that war, and the only Western settlements were those created by German settlers and focussed on coconut plantations and missionary undertakings.
As noted above, the most senior Japanese command echelon in the theatre was Imamura’s 8th Area Army headquartered in Rabaul on the north coast of New Britain and controlling the activities of the 200,000 or so men of Hyakutake’s 17th Army in the Solomon islands group, Adachi’s 18th Army on New Guinea, and the smaller Japanese formations and units holding the Bismarck islands group.
It was in January 1942 that the Japanese had taken the strategically important port of Rabaul in north-eastern New Britain in 'R', and in the months which followed the Japanese built their largest and most important naval and air bases in the Pacific in that area. Early in 1943 the Japanese leadership in Tokyo had expected that the Allies would attempt to break the inner Japanese defensive belt in the Pacific and attack the bases on New Guinea, the Mariana islands group, Palau and other bases in the Caroline islands group, and the Philippine islands group. Imamura therefore foresaw an attack on New Britain at the latest after the Allies had occupied New Ireland, to the north of New Britain, which was expected in February or March 1944.
As a result of the Allies' already rampant and steadily growing air superiority, the 8th Area Army had by this time been compelled to rely exclusively on barges and submarines for the movement of men and supplies between Rabaul and New Guinea to the south and the Solomon islands group to the south-east. In September 1943, Matsuda took command of the 65th Independent Mixed Brigade, the various pioneers and debarkation units, and a number of troops of Nakano’s 51st Division, whose main units were on New Guinea and heavily committed in fighting the Australians. Two companies of the 115th Division, provisional infantry companies formed from the artillery and engineer elements of the 66th Division, and about half of the 51st Reconnaissance Regiment were incorporated in the 65th Independent Mixed Brigade, which had its headquarters near the airfield at Cape Gloucester. On 5 October 1943 the 65th Independent Mixed Brigade came under the command of the 17th Division, which was commanded by Sakai, an arrival from the Chinese theatre in December 1943.
Sakai established his headquarters at Malalia in the vicinity of Cape Hoskins on the eastern side of the Willaumez peninsula. The 17th Division immediately embarked on the process of enlarging the existing defence lines. The divisional headquarters was established in an existing concrete bunker at the foot of Mt Talawe, which was surrounded by dense vegetation. Smaller bunkers and shelters for machine gun positions were sited at possible Allied landing beaches 5 miles (8 km) to the south-east of Cape Gloucester. Two hills, later known as Target Hill and Hill 660, were the focal points of the Japanese defences. Thus about half of the Japanese troops in the western part of New Britain were in positions which could contribute effectively to the defence of Cape Gloucester.
On 12 December Sakai advised all his subordinate commanders that an Allied invasion was imminent. The large numbers of Allied landing ships and craft in harbours along the coast of Papua and North-East New Guinea could not provide the Japanese with any indication of the scheduling and location of Allied amphibious operations, however, and false invasion alerts were commonplace up to the end of 1943. However, the increase of the Allies' air superiority and the weight of the bombing of Rabaul and Wewak were strong indications that the 'Backhander' invasion of New Britain by Lieutenant General Walter C. Krueger’s 6th Army was imminent.
This defence effort was focused on the western end of New Britain island. The 65th Independent Infantry Brigade had been sent from Rabaul in May to take control of the shipping engineer units located in this region, and thus to ensure the barge route to New Guinea was kept open. In September the brigade was consolidated with the 4th Shipping Command and elements of the 17th Division and 51st Division to create the 'Matsuda' Force, and this force held the area of Cape Gloucester, the Willaumez peninsula and Umboi island off the western end of New Britain; it also deployed two detachments on the south-west coast at Cape Merkus and Cape Busching.
Sakai’s 17th Division (53rd, 54th and 81st Regiments less several battalions deployed to other islands) was redeployed from China between October and November, and established its headquarters at Gavuvu to the east of the Willaumez peninsula.
Kagesa’s 38th Division (228th, 229th and 230th Regiments), together with the 8th Area Army and detachments from other units, garrisoned Rabaul.
'Backhander' was an initial step in the southern component of the 'Elkton' plan agreed in April 1943 to cut off and isolate, at the eastern end of New Britain and in New Ireland, the 8th Area Army, which would then be left 'to wither on the vine' for the rest of the war as the Allies pushed on toward the Japanese home islands.
'Backhander' was preceded by the 'Director' (i) capture of the Arawe peninsula, on the south coast of New Britain to the east of Cape Gloucester, as a PT-boat base and also to divert Japanese eyes from the island’s north coast. The peninsula had been taken with little difficulty on 15 December 1943 by Brigadier General Julian W. Cunningham’s 112th Cavalry of Major General Innis P. Swift’s 1st Cavalry Division. The Japanese slowly moved two battalions from Rabaul by along the coast by barge and overland along jungle trails, and these were able to attack the US positions from the end of the month. The attack was beaten back, and in mid-January 1944 Cunningham’s men, reinforced by tanks and artillery, destroyed the last vestiges of a Japanese capability round their perimeter.
Two days after the decision to proceed with 'Backhander' had been taken, the 6th Army’s Alamo Scouts began to deploy in the area of Cape Gloucester. The men of this reconnaissance unit approached the coast by PT-boat, then transferred to dinghies to land on the beaches. From there they reconnoitred the Japanese defences by direct observations or through contact with the local aboriginal population of New Britain.
The 'Backhander' Task Force embarked on the ships of Task Force 76 ('Backhander' Attack Force) at Milne Bay at the south-eastern tip of Papua, Cape Sudest and Cape Cretin. Under the command of Rear Admiral Daniel E. Barbey, TF76 (7th Amphibious Force) was thus responsible for the delivery of some 13,000 men of Rupertus’s 1st Marine Division. The first echelon comprised the APD Task Group Beach Yellow 1 with the converted destroyers Stringham, Crosby, Kilty, Dent and Ward carrying 720 men of the 3/7th Marines, and APD Task Group Beach Yellow 2 with Brooks, Gilmer, Sands, Humphreys and Noa carrying 720 men of the 1/7th Marines; the second echelon comprised LCI Task Unit Beach Yellow 1 with six infantry landing craft carrying 720 men of the 2/1st Marines, and LCI Task Unit Beach Yellow 2 with four infantry landing craft carrying 720 men of the 3/1st Marines. The first and second echelons were supported by the Escort Force with the destroyers Shaw, Conyngham, Flusser, Mahan, Reid and Smith, and controlled by the Beach Yellow Harbor Control Unit with two submarine chasers and three yard minesweepers.
Gunfire support was the task of Task Group 74.1 (Cruiser Bombardment Unit) commanded by a British officer, Rear Admiral V. A. C. Crutchley and comprising the Airdrome Section with the Australian heavy cruisers Australia and Shropshire, Australian destroyers Arunta and Warramunga, and US destroyers Helm and Ralph Talbot, and Rear Admiral Russell S. Berkey’s Task Group 74.2 (Yellow Beach Section) with the US light cruisers Nashville and Phoenix escorted by the US destroyers Bush, Ammen, Bach and Mullany of Destroyer Division 48.
The third echelon comprised seven tank landing ships each carrying 500 men and 150 tons of bulk stores as well as artillery and vehicles, and escorted by the destroyers Drayton, Lamson, Mugford and Bagley.
The fourth echelon comprised 14 mechanised landing craft and 12 tank landing craft carrying 1,500 men of the 21st Battalion Landing Team, artillery, vehicles and 575 tons bulk stores, and supported by two rocket-armed DUKW amphibious trucks, two large submarine chasers, one small submarine chaser, five infantry landing craft, and the destroyers Reid and Smith.
The fifth echelon comprised seven task landing ships each carrying 480 men of Combat Teams B and C and 150 tons of bulk stores, vehicles and tanks, and supported by the destroyers Hutchins, Beale, Daly and Brownson. The last was sunk in an attack by 60 Japanese aircraft; Shaw was badly damaged, and Drayton, Lamson, LST-66 and LST-202 were less seriously damaged.
The sixth echelon comprised five tank landing ships each carrying 240 men of the 12th Marine Defense Battalion and medical detachment, 250 tons of bulk stores, vehicles and artillery, supported by three large submarine chasers, the destroyers Flusser and Mahan, and the tug Sonoma.
The seventh echelon comprised five tank landing ships each carrying 250 marine engineers, 250 tons of bulk stores, vehicles and artillery, and supported by the tug Reserve, three small submarine chasers and the destroyers Drayton, Lamson, Mugford and Bagley.
The Reserve Group comprised the Australian infantry landing ship Westralia, US dock landing ship Carter Hall and US cargo ship Etamin.
Based on Matsuda’s 65th Independent Mixed Brigade, the Japanese order of battle in the Cape Gloucester area comprised two battalions of the 53rd Regiment: the the rest of the 53rd Regiment and the 141st Regiment were deployed too far from Cape Gloucester to affect the outcome of the campaign. There were also some 20 Japanese aircraft at Cape Gloucester.
On 24 December the light cruisers Cleveland, Columbia and Montpelier, in company with four destroyers, shelled Buka and Buin near Bougainville as a diversion, and on 27 December a task force led by Rear Admiral Walden L. Ainsworth repeated the shelling near Kieta.
Air support was provided by attacks by aircraft of the Air Solomons command against Rabaul, a carrierborne air attack against Kavieng, and US 5th AAF attacks against Cape Gloucester itself. The Japanese nonetheless managed to get sufficient scout aircraft into the air to detect the 'Backhander' assault convoy, but Vice Admiral Junichi Kusaka, the commander of the 11th Air Fleet, estimated that it was making toward the 'Director' (i) beach-head at Arawe, which had been established on 15 December 1943 as a diversion, and most of the Japanese air power was directed there for a major air counterattack on 27 December. Thus the diversion had worked.
The assault force sailed on 25 December and passed through the Dampier Strait. The Cape Gloucester area had been subjected to heavy bombing for the previous month, so the Japanese rightly suspected that the area would be assaulted from the sea.
TF76 divided into the Western and Eastern Attack Groups before dawn on 26 December. The former carried the 2/1st Marines toward a beach to the north of the village of Tauali on the western end of New Britain and 8 miles (13 km) to the south-west of Cape Gloucester. The task of this force was to block the coastal trail and so prevent units of the 65th Independent Mixed Brigade, located in the south and at Borgen Bay to the east of the main landing, from cutting across on an inland trail passing just to the south of Mt Talawe at the western end of the island and then moving north to Cape Gloucester.
The 1,500 men of this group landed without opposition at 07.48, finding only abandoned positions, and soon established their trail block on the ridges facing the sea.
The latter attack group continued to Cape Gloucester and, after a heavy naval bombardment, landed the 7th Marines on two beaches on the north-western flank of Borgen Bay at 08.05, again without encountering Japanese opposition, and immediately started to move inland. The 1st Marines soon followed its sister regiment. The divisional reserve was the 5th Marines, and this landed on 28 December. On the same day the 7th Marines became the Assistant Division Commander Group to secure the beach-head’s eastern flank as the rest of the division advanced to the west in the direction of the airfields. The marines met only very modest resistance during the day as they consolidated the beach-head, but were severely constrained by the presence of inland swamps.
Thus some 13,000 marines and 7,600 tons of supplies were landed on the operation’s first day. The Japanese responded with an attack at 14.30 by 20 Auchi D3A 'Val' dive-bombers and 50 to 60 fighters. These were detected at a range of 60 miles (100 km) out by destroyer radar, but the four squadrons of Lockheed P-38 Lightning fighters providing air cover missed the interception. The Japanese sank the destroyer Brownson with heavy loss of life, and badly damaged Shaw with near-misses that sprayed the hull with shrapnel. Subsequent attacks did little more damage, and heavy weather from 29 December onward halted all Japanese air activity.
The same weather meant wretched conditions for the ground troops. However, the discovery of a small beach farther to the west that was suitable for landing supplies relieved some of the logistical pressure. Marine engineers and the men of the 19th Naval Construction Battalion were able to construct roads and bridges to support the advance. This was fortunate as the monsoon set in on 28 December, with rainfall as great as 16 in (405 mm) per day, which made the existing coastal road impassable.
US Army engineers and an Australian radar station were established on unoccupied Long island, some 80 miles (130 km) to the west of Cape Gloucester on the same day.
The 17th Division immediately ordered the 'Matsuda' Force to counterattack the US landings. All of this force’s scattered units, including part of the 51st Reconnaissance Regiment on Rooke island, then started to converge on the US beach-head.
The marines fought their way to the west against increasing resistance, and by noon on 31 December had taken the area’s two airfields. The Japanese counterattacked the trail block of the 2/1st Marines on 30 December, but this effort was driven back with ease. On 2 January 1944 one company from the Cape Gloucester perimeter reached the trail block and reported no significant Japanese activity, and the blocking battalion was withdrawn by landing craft on 5 January to rejoin the rest of the division.
On 2 January the marines on the eastern flank made their first attack toward Borgen Bay, and ran into a very determined resistance based on difficult terrain features along what became known as Suicide Creek. The Japanese also counterattacked toward Target Hill on the marines' extreme eastern flank during the following morning, but gained no ground in attacks which were not effectively co-ordinated. The marines continued their push to the east, but the terrain, weather and sturdy resistance slowed the advance to little more than a crawl. It took the marines more than two weeks to advance slightly more than 3 miles (4.8 km).
By now the Japanese had realised that the US strength on Cape Gloucester was too great to be checked, let alone defeated, by the forces they had available in the area, and that only air attacks now stood any chance of slowing the construction of US airfields. The 'Matsuda' Force was therefore ordered to withdraw to the east on 21 January.
US construction work on Airfield No. 2 progressed, but the smaller Airfield No. 1 to its west was abandoned as it soon became clear that it was not worth the effort to continue its construction in ever-thickening mud. No. 2 Airfield became operational, with a runway 4,200 ft (1280 m) long, only on 31 January, but a longer runway was never completed.
At Arawe the US and Japanese forces continued to probe each other until 16 January, when an American attack dislodged the Japanese dug in on the US perimeter. The Japanese then pulled back to the Lupin airstrip, which they believed to be the US objective, but now came to think that the Americans were building a major airfield within their perimeter. The two sides maintained desultory action until 24 February, when the Japanese were ordered to join the general withdrawal to the east.
A US Marine patrol from Cape Gloucester and a US Army patrol from Arawe met at the village of Gilnit on 16 February, and a marine company landed on abandoned Rooke island on 12 February. During this same period increasingly heavier air attacks on Rabaul continued to weaken the defences of this Japanese base area still further. Marine patrols pushed out to the south and east from the perimeter throughout February as the Japanese undertook an orderly withdrawal.
The 17th Division planned to establish defensive positions to the west of the Willaumez peninsula on the north coast and Gasmata on the south coast. The 8th Area Army and South-Eastern Area Fleet decided, however, that more would be gained by a withdrawal of the 17th Division to the east for the establishment of a strong perimeter around Rabaul rather than expending a significant portion of the division’s strength in any attempt to halt the US advance in a jungle whose general impenetrability made the delivery of supplies almost impossible. Thus on 23 February the 17th Division was ordered to withdraw to the east.
The remnants of the 'Matsuda' Force were still moving fitfully to the east but were still two weeks' movement from the Willaumez peninsula on the assumption that an escape route could be kept open. The 51st Reconnaissance Regiment served as a rearguard to slow the US progress while the battalion-sized 'Terunuma' Force, organised by the 54th Regiment, was to defend the Willaumez peninsula area as the remnants continued their retreat to Rabaul.
On the same date that the leading units of the 'Matsuda' Force reached the base of the Willaumez peninsula, the marines landed mid-way up the peninsula’s length in 'Appease', designed to cut off the withdrawing Japanese forces. Most of the 17th Division managed to reach the area of Rabaul by the end of March. The last rearguard element was destroyed on 30 March, but in overall terms the Japanese rearguard action and retirement had been completed successfully.
Some 3,100 Japanese had been killed at a cost 248 marines killed and another 772 wounded. Some 25 deaths were due to falling trees in the swamps, whose roots were loosened by the heavy rain and the artillery barrage.
The terrible weather conditions proved more memorable for many marines than the Japanese resistance. Hot food was impossible to prepare in the constant downpours, and marines hoarded the waxed paper and cardboard from K ration containers as a source of fuel for heating coffee. Anything made of leather quickly developed a layer of blue mould that had to be scraped off every day. It was impossible for the marines to keep their feet dry, and trench foot became a serious problem.
On 26 March the US Navy established a PT-boat base at Gaur Harbour, and the activities of these boats soon swept the north coast clean of Japanese barge traffic as far east as the Gazelle peninsula. Native scouts led by officers of the Special Operations Australia organisation harassed Japanese patrols venturing out of the Rabaul perimeter.
Major General Rapp Brush’s 40th Division (108th, 160th and 185th Infantry) started to relieve the 1st Marine Division at Cape Gloucester on 23 April, so ending 'Backhander' proper, and the last marines had departed by 4 May. The casualties up to this time had been 310 US dead and 1,083 wounded, and more than 1,000 Japanese killed in action.
The 40th Division was involved in only sporadic and small-scale action and its units patrolled the western part of New Britain. On 7 May the division occupied the Cape Hoskins airfield on the central part of the north coast, in June relieved the 112th Cavalry in its 'Director' (i) beach-head at Cape Merkus, and in October occupied Gasmata.
In the summer of 1944 the Japanese activated the 39th Independent Mixed Brigade on New Ireland from replacements and remnants of other units.
On 27 November Major General Alan H. Ramsay’s (from 4 April 1945 Major General Horace C. H. Robertson’s) Australian 5th Division (4th, 6th and 13th Brigades) began to relieve the 40th Division, but the whole of the Australian division was not assembled on New Britain until February 1945. The division then continued to harass the Japanese and moved its bases farther to the east. Elements of the Australian division were soon deployed as far east as the isthmus, leading to the Gazelle peninsula, between Open Bay and Wide Bay, and were involved in only light action in that area through the early months of 1945, and there was only limited patrol action by each side for the remainder of the war.
Lieutenant General Sir Vernon Sturdee, commander of the Australian 1st Army, accepted the Japanese surrender at Rabaul on 6 September. Allied estimates of the Japanese strength at Rabaul had been between 32,000 and 38,000 men, a few aircraft and no ships other than barges. After the surrender the Allies were amazed to learn that there were 53,000 soldiers, 16,000 sailors and 20,000 civilian labourers trapped inside the Rabaul perimeter, which was strongly fortified and measured 16 by 28 miles (26 by 45 km).
In strategic terms the New Britain campaign, which had cost the Japanese something in the order of 4,000 dead and 420 taken prisoner before the final surrender, was not as important as the seizure of other islands in the Bismarck islands archipelago, especially as the Allies had no need to develop the island as a major troop-staging, naval or air bases.
The Admiralty islands archipelago to the north-west offered a better harbour and was closer to objectives in the Marshall and Caroline island groups. Even so, 'Backhander' did provide the forces of the South-West Pacific Area command with an important airfield, which became operational on 1 January 1944, for the support of further operations, including 'Michaelmas' and 'Dayton', to the west along the north coast of New Guinea toward Saidor and Madang, and to points still farther to the north-west.