Operation Ringbolt

This was the US seizure of Tulagi, Gavutu and Tanambogo islands off the larger Florida island in the Solomon islands group in parallel with the ‘Watchtower’ landing on Guadalcanal island (7 August 1942).

Tulagi is a small island, just 3,000 yards (2745 m) long and 880 yards (800 m) wide, located just 440 yards (400 m) off the south coast of Florida island to the north of Guadalcanal. It is a rugged coral ridge, reaching a maximum height of about 330 ft (100 m). There are reefs off most of the island’s south-west coast, with a gap in the centre of the coast, and Tulagi harbour is located to the north-east of the island’s northern end. The island was the seat of British administration in the Solomon islands group, largely because its climate is more bearable for Europeans than any other island of the Solomons group with a good anchorage. Nevertheless, the climate was uncomfortably damp, with an average annual rainfall of 164 in (4165 mm).

About 3,000 yards (2745 m) to the east of Tulagi are the small islets of Gavutu and Tanambogo. To the east of these islets is another good anchorage, Gavutu harbour. The islets were connected by a causeway, and a copra company had its local headquarters, warehouses and wharves on Gavutu.

Florida island itself is mountainous, with a maximum height of more than 2,000 ft (610 m). It is covered with jungle and has practically no beach, the coast being backed by steep hills along almost its entire length. This made the island itself of little military value in World War II. However, there was a roomy but undeveloped anchorage at Purvis Bay, to the south-east of Gavutu and Tanambogo. Tulagi harbour and Purvis Bay together constitute the best deep-water anchorage in the Solomon islands group.

The Australians stationed some Consolidated PBY Catalina flying boats here after the outbreak of war in the Pacific. When the Japanese began bombing the island in January 1942, most of the residents were evacuated, and the small garrison was similarly evacuated on 2 May.

Under the overall command of Rear Admiral Kiyohide Shima, who provided the minelayer Okinoshima, destroyers Kikutsuki and Yuzuki, eight auxiliary minesweepers, some smaller naval vessels and one transport ship, a detachment of Commander Masaaki Suzuki’s 3rd Kure Special Naval Landing Force had occupied the larger Florida island, just to the north of these three small islands, on 3 May and then occupied the smaller islands with the intention of establishing a seaplane base between the main island and the small islands just off its southern shore. The ships in Tulagi harbour were raided by 99 of the US fleet carrier Yorktown’s aircraft during the following day, the attack sinking the destroyer Kikutsuki and three minesweepers, as well as damaging four other ships, in a prelude to the Battle of the Coral Sea.

While on Guadalcanal the US forces involved in ‘Watchtower’ later encountered little but thick jungle, voracious insects and sapping, humid heat, the conditions faced by the Japanese around Florida island were notably more favourable for the men of the Kure 3rd Special Naval Landing Force, 14th Construction Unit, Tulagi Communications Base, and Captain Shigetoshi Miyazaki’s ‘Yokohama’ Air Group (18 floatplanes) of Rear Admiral Sadayoshi Yamada’s 25th Air Flotilla, totalling some 550 men on Gavutu and Tanambogo, and 350 men on Tulagi under Suzuki’s local command. In overall command on Guadalcanal and the islands to its north was Miyazaki.

On 28 May Admiral Chester W. Nimitz, commanding the Pacific Ocean Areas, proposed that the 1st Marine Raider Battalion raid Tulagi, but the plan was rejected after General Douglas MacArthur, commanding the South-West Pacific Area, pointed out that the Allies had insufficient strength at the time to hold the island.

The Allies were fully aware of the Japanese construction effort on Tulagi, but their concerns were increased early in July 1942 when they learned that the Japanese navy had started to construct a large airfield near Lunga Point on nearby Guadalcanal: landplane bombers operating from such a base would pose a considerably greater threat, in terms of operational radius and weight of bombload, than seaplanes operating from Tulagi. By August 1942, the Japanese had about 900 troops on Tulagi and nearby islands, and 2,800 personnel, of whom many were Japanese and Korean construction specialists and labourers, on Guadalcanal. When completed, the airfield would help to protect Japan’s major base at Rabaul, threaten Allied supply and communication lines, and establish a staging area for possible future offensives against the Fiji, New Caledonia and Samoa island groups as projected in 'Fs'.

The Allied plan to attack the south-eastern end of the Solomon islands group was conceived by Admiral Ernest J. King, commander-in-chief of the US Fleet and the Chief of Naval Operations. It was King who proposed the offensive as the means firstly of denying to the Japanese any use of the south-eastern end of the Solomon islands group to threaten the supply routes between the USA and Australasia, and secondly of using them as the starting points for a campaign whose object would be the seizure if the major Japanese base at Rabaul while also supporting the Allied campaign on New Guinea. Success at Rabaul and on New Guinea, King believed, would open the way for US forces to retake the Philippine islands group.

As a result, Nimitz created the South Pacific Area command, headed by Vice Admiral Robert L. Ghormley, to direct the Allied offensive in the Solomon islands group.

In preparation for the offensive, in May 1942 Major General Alexander A. Vandegrift was ordered to move his 1st Marine Division from the USA to New Zealand, and other Allied land, sea and air force units were sent to establish bases in the Fiji, Samoa and New Caledonia island groups. Espíritu Santo in the New Hebrides islands group was chosen as the headquarters and main base for the forthcoming offensive, which was to be launched on 7 August as 'Watchtower'. The Allied offensive was initially aimed only at Tulagi and the Santa Cruz islands group, omitting Guadalcanal. It was at this stage, however, that Allied reconnaissance discovered the Japanese airfield construction efforts on Guadalcanal, which now became the primary target. At the same time the Santa Cruz islands group was dropped from the operation.

Local command was vested in Vice Admiral Frank J. Fletcher, flying his flag in the fleet carrier Saratoga, and in command of the amphibious forces was Rear Admiral Richmond K. Turner. The 'Watchtower' expeditionary force of 75 warships and transports, which included US and Australian vessels, assembled near Fiji on 26 July, and undertook a single rehearsal landing before departing for Guadalcanal on 31 July with Vandegrift as the overall commander of the 16,000 Allied (primarily US Marine) ground forces involved in the landings and in personal command of the assault on Guadalcanal. In command of the force of 3,000 US Marines which was to take Tulagi and the nearby islands of Florida, Gavutu, and Tanambogo was another US officer, Brigadier General William H. Rupertus, assistant divisional commander of the 1st Marine Division, on the transport ship Neville.

Adverse weather allowed the expeditionary force to reach the area of Guadalcanal during the morning of 7 August without being detected by the Japanese, through the Japanese did finally detect the invasion force’s radio traffic and prepared to send scout aircraft aloft at daybreak. In what later came to be known as 'Ironbottom Sound' between Tulagi in the north and Guadalcanal in the south, the ships of the invasion force divided into two groups, with the larger group assigned to the assault on Guadalcanal and the smaller group tasked with the assault on the islands of Florida, Tulagi and causeway-linked Gavutu and Tanambogo.

Warplanes from the fleet carrier Wasp dive-bombed Japanese installations on Florida, Tulagi, Gavutu and Tanambogo, destroying 15 Japanese seaplanes floating in the anchorages near the islands. Several of the seaplanes were warming their engines as they prepared to take-off and were lost with their aircrews and many of their support personnel.

The US light cruiser San Juan and destroyers Monssen and Buchanan undertook a gunfire bombardment of the planned landing sites on Tulagi and Florida islands, and in order to cover the assaults on Tulagi, Gavutu and Tanambogo, marines of Lieutenant Colonel Robert E. Hill’s 1/2nd Marines made an unopposed landing on Florida island at 07.40 in the area of Haleta. The marines were guided to their objective by several Australians familiar with the Tulagi and Florida area from having lived and worked in the area.

The assaults on Tulagi, Gavutu, and Tanambogo were a complex undertaking, in part as the shortage of landing craft made it impossible to attack all three of the objectives simultaneously, and the assault on the causeway-linked islands of Gavutu and Tanambogo was further complicated by the presence offshore of reefs, which forced the landing craft to loop round from the transport area, to the south-west of Tulagi island, past the eastern end of Gavutu island before delivering their troops on the eastern side of this island.

The forces for ‘Ringbolt’ were part of Turner’s Task Force 62 (South Pacific Amphibious Force), and more specifically Task Group 62, which had two components. The first of these was TG62.1 (Convoy). This was divided into Transport Group Yoke carrying Rupertus’s 3,900 marines: the transport ships ships Neville, Zeilin, Heywood and President Jackson of Transport Division E carried the 2/5th Marines, 2/2nd Marines, Battery E of the 11th Marines, elements of the 3rd Marine Defense Battalion, 1st Marine Parachute Battalion and elements of the 1st Marine Raider Battalion; and Transport Division 12 carrying the 1st Marine Raider Battalion (less one company) in the high-speed destroyer transports Colhoun, Little, McKean and Gregory. Warship support was provided by Rear Admiral Norman Scott’s Task Group 62.4 (Fire Support Group M) with the light cruiser San Juan and the destroyers Monssen and Buchanan

At 08.00 two battalions of US marines, in the form of Lieutenant Colonel Merritt A. Edson’s 1st Raider Battalion and the 2/5th Marines, landed without opposition on Blue beach along the western shore of Tulagi, about half-way between the two ends of the island. The presence of coral beds near the shore prevented the landing craft from reaching the beach, but the marines were able to wade the remaining 100 yards (90 m) without hindrance from the Japanese forces, who were apparently taken by surprise by the landings and had yet to get together any organised resistance. At this time, the Japanese forces on Tulagi and Gavutu, which were a detachment of the 3rd Kure Special Naval Landing Force and men of the ‘Yokohama’ Air Group, under Miyazaki’s command, signalled Captain Sadayoshi Yamada, their commander at Rabaul, that they were under attack, were destroying their equipment and papers, and ended with the fact that the US troop strength was overwhelming and that they would defend to the last man. Suzuki, commander of the special naval landing force unit, ordered his naval infantry into pre-prepared defensive positions on Tulagi and Gavutu.

The men of 2/5th Marines secured the north-western end of Tulagi without opposition and then joined 1st Raider Battalion in an advance toward the south-eastern end of the island with its B, D, A and C Companies in line abreast from left to right. The marines advanced throughout the day, in the process defeating a few isolated pockets of Japanese resistance. At about 12.00, Suzuki repositioned his main strength into a line to the north-west of Hill 281 and a nearby ravine at the south-eastern end of the island. The Japanese defences included many tunnelled caves dug into the hill’s limestone cliffs and machine gun positions protected by sandbags. The marines reached these defences toward the end of daylight, appreciated that an attack could not be completed before the onset of the dark hours, and therefore dug in for the night.

During the night of 7/8 August, the Japanese attacked the marine lines five times, the first of them at 22.30. The attacks took the form of frontal charges as well as individual and small unit infiltration efforts towards Edson’s command post, and at times resulted in hand-to-hand combat with the marines. The Japanese made a breakthough and captured a machine gun, but were thrown back soon after this. After taking a few more casualties, the marines held their line for the rest of the night, and the Japanese suffered heavy losses in their tactically inefficient attacks.

As dawn broke on 8 August, six Japanese infiltrators hiding under the porch of the former British colonial headquarters shot and killed three marines, but within five minutes the six had been killed with grenades. Later in the morning, after reinforcements in the form of the 2/2nd Marines had been landed, the marines surrounded Hill 281 and the ravine, pounded both locations with mortar fire, and then assaulted the two positions, using improvised explosive charges to kill the Japanese defenders taking cover in the many caves and fighting positions spread throughout the hill and ravine. Thus the individual Japanese fighting positions were destroyed one by one. Effective Japanese resistance had ended by the afternoon, although a few stragglers were found and killed over the next few days.

The fight for Tulagi had cost the Japanese 307 men killed, and the marines 45 men killed. Three Japanese were taken prisoner.

The nearby islets of Gavutu and Tanambogo, to the south-east of Tulagi, accommodated the Japanese seaplane base, on the north-eastern side of Gavutu islet, as well as 536 Japanese naval personnel from the ‘Yokohama’ Air Group and 3rd Kure Special Naval Landing Force as well as Korean and Japanese civilian technicians and labourers of the 14th Construction Unit.

The two islets are little more than mounds of coral and were connected to each other by a straight causeway about 1,600 ft (490 m) long. The hills on Gavutu and Tanambogo were called Hill 148 and Hill 121 respectively by the marines because of their height in feet (45 and 37 m). On each of the islets the Japanese were well entrenched in bunkers and caves constructed on and into the two hills, and the islets were mutually supportive since each was in machine gun range of the other. The Americans erroneously believed that the islets were held by only 200 naval troops and construction workers.

At 12.00 on 7 August, 397 men of the US 1st Marine Parachute battalion assaulted Gavutu from the north-east against the islet’s north-eastern tip. The assault was scheduled for 12.00 because there were not enough aircraft to provide cover simultaneously for the Guadalcanal, Tulagi and Gavutu landings. The preceding naval gunfire bombardment had damaged the seaplane ramp, so the landing craft had to deliver the marines to a more exposed location on a nearby small beach and dock. Japanese machine gun fire began to inflict heavy casualties, killing or wounding about 10% of the marines as they landed and started to scramble inland in an attempt to get out of the crossfire directed at them by machine guns on each of the islets.

The surviving marines were able to deploy two 0.3-in (7.62-mm) Browning machine guns to provide suppressing fire on Gavutu’s caves, and this made it possible for more marines to drive inland from the landing area. Even so, many marines sought cover and the US force became scattered and was quickly pinned down. Captain George Stallings ordered the marines to use their machine guns and mortars to deliver suppressive fire onto the Japanese machine gun positions on Tanambogo, and shortly after this US dive-bombers dropped several bombs on Tanambogo, which served to reduce some of the considerable volume of fire which had been coming from the islet.

After about two hours, marines reached and climbed Hill 148 and the, working their way from the top began to clear the Japanese fighting positions on the hill, most of which were still in action, with explosive charges and grenades, although they was also some hand-to-hand combat. From the top of the hill the marines were also able to lay a greater volume of suppressive fire on Tanambogo. Major Robert H. Williams, the marine battalion commander on Gavutu, radioed Rupertus with a request for reinforcements before attempting to assault Tanambogo.

Most of the 240 Japanese defenders on Tanambogo were aircrew and maintenance personnel of the ‘Yokohama’ Air Group as well as many construction personnel. Most of them was neither trained nor equipped for any combat role. Rupertus detached B Company of the 1/2nd Marines on Florida island for the assault on Tanambogo, despite advice from members of his staff that one company was inadequate. Incorrectly believing that Tanambogo was only lightly defended, this company attempted an amphibious assault directly on Tanambogo at 20.30 on 7 August but, illuminated by fires resulting from the US naval gunfire bombardment of the islet, the five landing craft carrying the marines came under heavy fire as they approached the shore, many of the US Navy boats’ crews being killed or wounded, and three of the boats being damaged. Realising the position was impossible, the marine company commander ordered the remaining boats to depart with the wounded marines, and he and 12 men who had already landed sprinted across the causeway to cover on Gavutu. The Japanese on Tanambogo suffered the loss of 10 men killed in the day’s fighting.

Throughout the night, as the Japanese made isolated attacks on the marines on Gavutu under the concealment of heavy thunderstorms, Vandegrift prepared to send reinforcements to assist with the assault on Tanambogo, and the 3/2nd Marines, still embarked on ships off Guadalcanal, was notified to prepare to assault Tanambogo on 8 August 8. The battalion began to come ashore on Gavutu at 10.00 on 8 August and assisted in the destruction of the remaining Japanese defences on that islet, which was completed by 12.00. The battalion then prepared to assault Tanambogo, with the marines on Gavutu provided covering fire. In preparation for the assault, US carrierborne dive-bombers and naval gunfire bombardment were requested. After the carrier aircraft twice accidentally dropped bombs on the marines on Gavutu, killing four of them, further carrier aircraft support was cancelled. San Juan placed its shells on the correct island, however, and shelled Tanambogo for 30 minutes. Delivered from Gavutu, the marine assault began at 16.15, both by landing craft and across the causeway. With the support of two marine M3 light tanks, the marines started to make progress against the Japanese defences. One of the tanks became stuck on a stump and isolated from its infantry support, however, and was surrounded by some 50 Japanese airmen, who set fire to the tank, killing two of its crew and severely beating the other two members of the crew before most of them were killed by marine rifle fire. The marines later counted 42 Japanese bodies around the burned-out hulk of the tank, including the corpses of the ‘Yokohama’ Air Group’s executive officer and several pilots. The commander on Tanambogo was Miyazaki, who blew himself up inside his dug-out late in the afternoon of 8 August.

Throughout the day, the marines methodically destroyed the islet’s caves with explosive charges in a process completed at 21.00. The few Japanese still alive made isolated attacks throughout the night, and there were several hand-to-hand engagements. By 12.00 on 9 August, all Japanese resistance on Tanambogo had been rough to an end.

In the battle for Gavutu and Tanambogo, 476 Japanese and 70 marines or naval personnel had died. Of the 20 prisoners taken during the battle, most were not Japanese combatants but Korean labourers of the Japanese construction unit.

During the battle, about 80 Japanese had managed to make their escape from Tulagi, Gavutu and Tanambogo by swimming to Florida island. They were all hunted down and killed by marine and British Solomon Islands Protectorate Defence Force patrols over the next two months.

The Allies quickly turned the Tulagi anchorage into a naval base and refuelling station. During the Guadalcanal and subsequent stages of the campaign in the Solomon islands group, Tulagi served as an important base for Allied naval operations. Since the Japanese exerted control over the nearby seas at night throughout the Guadalcanal campaign, any Allied ships which could not depart the Guadalcanal area by the fall of night frequently took refuge in Tulagi’s harbour. Allied ships damaged in the naval battles between August and December 1942 in the vicinity of Guadalcanal usually anchored in Tulagi harbour so that temporary repairs could be effected before the ships headed to rear-area ports for permanent repairs.

Later in the campaign, Tulagi also became a base for PT-boats trying to intercept the ‘Tokyo Express’ missions undertaken by Japanese warships to resupply and reinforce the Japanese forces on Guadalcanal. A seaplane base was also established on Florida island. Except for some troops left to garrison, defend, build and operate the base at Tulagi, the marines involved in ‘Ringbolt’ were soon relocated to Guadalcanal to help defend the captured airfield, later called Henderson Field, at Lunga Point, for it was to be on and round Guadalcanal that the crucial land and sea battles in the Guadalcanal campaign were to be fought.