The 'Battle of Tulagi and Gavutu-Tanambogo' was fought between US and Japanese forces primarily for the island of Tulagi in the Solomon islands groups of the South Pacific in the first stage of the Guadalcanal campaign (7/9 August 1942).

In this battle, US Marines of Major General Alexander A. Vandegrift’s 1^st Marine Division, with the marine landing and battle strength under the tactical command of Brigadier General William H. Rupertus, captured the islands of Tulagi, Gavutu and Tanambogo, among which the Imperial Japanese navy had constructed a naval and seaplane base. These 'Ringbolt' landings were resisted fiercely by the Japanese naval troops who, heavily outnumbered and outgunned by the Allied forces, fought and died almost to the last man.

While the landings on Tulagi and Gavutu-Tanambogo were taking place, Allied troops were also landing on nearby Guadalcanal in 'Watchtower' with the object of capturing an airfield under construction by Japanese forces. In contrast to the intense fighting on Tulagi and Gavutu, the landings on Guadalcanal were essentially unopposed. The landings on both Tulagi and Guadalcanal initiated the six-month Guadalcanal campaign and a series of combined-arms battles between Allied and Japanese forces in the Solomon islands group.

On 7 December 1941, the Japanese attacked the US Pacific Fleet at Pearl Harbor, and other targets in the Hawaiian islands group, this 'Ai' attack immediately initiating a state of war between the two nations. The attack crippled much of the US battleship fleet, but not the strategically more significant aircraft carrier force or the repair and fuel facilities at Pearl Harbor. Japan’s initial goals were to neutralise the Pacific Fleet, to seize South-East Asian territories rich in natural resources, and to establish strategic military bases constituting an outer defensive perimeter for Japan’s empire in Asia and the Pacific. In support of these goals, Japanese forces attacked and took control of the Philippine islands group, Thailand, Hong Kong, Malaya, Singapore, the Netherlands East Indies, Wake island, the Gilbert islands group, New Britain, New Ireland and Guam.

Two attempts by the Japanese to extend their defensive perimeter in the south and central Pacific were thwarted in the 'Battle of the Coral Sea' in May 1942 and the 'Battle of Midway' in June. These two strategic victories provided the Allies with an opportunity to take the initiative and launch an offensive against the Japanese somewhere in the Pacific, and for this the Allies selected the Solomon islands group, and specifically its south-eastern end in the form of Guadalcanal, Tulagi and Florida islands as the location for their first offensive.

As part of its 'Mo' undertaking that led to the 'Battle of the Coral Sea', the Imperial Japanese navy sent troops to occupy Tulagi and nearby islands in the south-eastern area of the Solomon islands group. These troops, primarily men of the 3^rd Kure Special Naval Landing Force occupied Tulagi on 3 May, and constructed a seaplane, ship refuelling and communications base on Tulagi and on the nearby islands of Gavutu, Tanambogo and Florida. All of these facilities were soon operational. Aware of the Japanese efforts on Tulagi, the Allies became increasingly concerned early in July when the Japanese began work on the construction of a large airfield near Lunga Point on nearby Guadalcanal. By August, 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 protect Japan’s major base at Rabaul on New Britain, threaten Allied supply and communication lines between the US west coast and Australia, and establish a staging area for the possible 'Fs' future offensives against Fiji, New Caledonia and Samoa.

The Allied plan to retake the south-eastern end of the Solomon islands group was conceived by Admiral Ernest J. King, the commander-in-chief of the US Fleet, who proposed the offensive to deny the use of the south-eastern end of the Solomon islands group by the Japanese as bases from which to threaten the supply routes between the USA and Australia, and to use them as starting points for a campaign to capture or neutralise the major Japanese base at Rabaul while also supporting the Allied land campaign on New Guinea, with the eventual goal of opening the way for US forces to retake the Philippine islands group. Admiral Chester W. Nimitz, the US commander-in-chief of the Pacific Ocean Areas, created the South Pacific Area under the command of Vice Admiral Robert L. Ghormley to direct the Allied offensive in the Solomon islands group.

The Florida island group lies 23 miles (37 km) to the north-north-east of Guadalcanal across the area of sea that became known as 'The Slot'. The Sealark Channel separates Guadalcanal and Florida at narrowest point of 'The Slot', 20 miles (32 km) wide. There are in fact three named channels defined by two parallel east/west lines of coral heads and reefs, with the Nggela Channel to the north of the Sealark Channel, and the Lengo Channel to the south; the entire passage is generally called the Sealark Channel.

Florida is actually a pair of islands separated by the Utaha Passage, which is only a few hundred feet wide, but was generally known to the US forces as a single island. Together, the islands are 23 miles (37 km) long and average 5 miles (8 km) in width. Florida island is ruggedly mountainous with elevations of over 2,000 ft (610 m). It is heavily forested right to the water’s edge. The few beaches are narrow and backed by steep hills. A number of small villages were scattered along the coasts with most of them connected by foot trails. Less than 2 miles (3.2 km) off Florida island’s north-western end across the Sandfly Passage is Olevuga island with Vatilau island 3 miles (4.8 km) beyond it. A number of small islands and islets are scattered around these two islands.

Despite its size, Florida island was relatively unimportant to the Guadalcanal campaign. Of greater importance was a cluster of small islands off this island’s southern central coast. These were the US assault’s first objectives. Tulagi island is 450 yards (410 m) off Florida, and is 1.75 miles (2.8 km) long on its north-west/south-east axis, 0.5 mile (0.8 km) wide, and some 3 miles (4.8 km) in circumference. The island is a 200 to 330 ft (61 to 101 m) high, a steep-sided coral ridge covered with trees, brush and cultivated areas around the villages scattered round the island. There are hills, knolls, ravines and caves all over the rugged island. The government residency and facilities were located near to and on the south-eastern end on low ground between Hills 330 and 230. The government wharves were located there on the north-east coast. The village of Sesapi was located on the north-eastern coast near the island’s north-western end. A small Chinese village was on this same side, just to the north of the residency. Coral reefs lie on the south-western side of the island with a 440-yard (400-m) gap on the central coast. This was the Beach Blue selected for the landing. Three islets stretch in a line to the south of Tulagi: the closest is Mbangai, only 100 yards (91 m) offshore, then Kokomtumbu and finally Songonangona 1,400 yards (1280 m) from Tulagi. The slightly larger island of Makambo lies 700 yards (640 m) to the north-east between Tulagi and Florida-Tulagi harbour.

Some 3,000 yards (2745 m) due east of Tulagi are Gavutu and Tanambogo islands connected by a 300-yard (275-m) concrete causeway, which survived the battle despite the fact that the Japanese had removed a 30-yard (27.5-m) section. The tiny Gaomi island, palm-covered and flat, lies 300 yards (275 m) to the east of Tanambogo, the most northerly of the two main islands. Gavutu measures about 250 by 500 yards (230 by 455 m) with a 175-ft (53-m) central peak. Tanambogo is 250 yards (230 m) across with a 148-ft (45-m) peak. Both islands are covered with brush and scatterings of palms, rugged and honeycombed with caves. Small wharves were located on both islands' north-eastern and eastern sides. The three islands are surrounded by coral reefs. About 1 mile (1.6 km) to the east is Florida’s Halavo peninsula, and Gavutu harbour lies between Gavutu island and this peninsula.

In preparation for the offensive, during May Vandegrift was ordered to move his 1^st Marine Division from the USA to New Zealand. Other Allied land, naval and air force units were sent to establish bases in Fiji, Samoa and New Caledonia. Espiritu Santo in the New Hebrides islands group was selected as the headquarters and main base for the impending 'Watchtower' offensive, which was to be launched on 7 August. At first it was planned that the Allied offensive would take only Tulagi and the Santa Cruz islands group, but not Guadalcanal, but after Allied reconnaissance efforts had discovered the Japanese airfield construction efforts on Guadalcanal, the seizure of this airfield was added to the plan and the Santa Cruz part of the operation was dropped.

The 'Watchtower' force of 75 warships and transport vessels, which included ships from both the USA and Australia, assembled near Fiji on 26 July, and engaged in one rehearsal landing before departing for Guadalcanal on 31 July. Vandegrift was in overall local command of the 16,000 Allied (primarily US Marine) ground forces involved in the landings and personally commanded the assault on Guadalcanal. In command of the 3,000 US Marines set to land on Tulagi and the nearby islands of Florida, Gavutu and Tanambogo was Rupertus on the US transport ship Neville.

Bad weather allowed the Allied force to arrive in the vicinity of Guadalcanal during the morning of 7 August without being detected by the Japanese, though the latter had heard the radio traffic of the Allied invasion force and prepared to send scout aircraft aloft at the break of day. The ships of the landing force divided into two groups, with the larger assigned to the assault on Guadalcanal and the smaller tasked with the assault on Tulagi, Florida and Gavutu-Tanambogo. Aircraft from the fleet carrier Wasp dive-bombed Japanese installations on Tulagi, Gavutu, Tanambogo and Florida, and also strafed and destroyed 15 Japanese seaplanes floating in the anchorages near the islands. Several of the seaplanes were warming their engines in preparation for take-off and were lost with their crews and many of their support personnel.

The light cruiser San Juan and the destroyers Monssen and Buchanan shelled the planned landing sites on Tulagi and Florida islands. To cover the assaults on Tulagi, Gavutu and Tanambogo, marines of the 1/2^nd Marines made an unopposed landing on Florida island at 07.40 after being guided to their objective by several Australians, such as Lieutenant Frank Stackpool, who were familiar with the Tulagi and Florida area from having previously lived and worked in the area.

At 08.00 on 7 August, two battalions of marines, including the 1^st Raider Battalion under Lieutenant Colonel Merritt A. Edson and the 2/5^th Marines under Lieutenant Colonel Harold E. Rosecrans made an unopposed landing on the western shore of Tulagi about mid-way between the two ends of the oblong-shaped island. Beds of coral near the shore kept the landing craft from reaching the shoreline, however, but the marines were able to wade the remaining 110 yards (100 m) without hindrance from the Japanese, who were apparently taken by surprise by the landings and had yet to begin any organised resistance. At this time, the Japanese forces on Tulagi and Gavutu, a detachment of the 3^rd Kure Special Naval Landing Force and members of the Yokohama Air Group under the command of Captain Shigetoshi Miyazaki, signalled their commander at Rabaul, Rear Admiral Sadayoshi Yamada, that they were under attack, were destroying their equipment and papers, and finally signed off with the message 'Enemy troop strength is overwhelming, We will defend to the last man.' Masaaki Suzuki, commander of the naval infantry unit, ordered his troops into pre-prepared defensive positions on Tulagi and Gavutu.

Men of the 2/5^th Marines secured the north-western end of Tulagi without opposition and then joined Edson’s battalion in its advance toward the south-eastern end of the island. The marines continued to advance throughout the day while destroying a few isolated pockets of Japanese resistance. At about 12.00, Suzuki repositioned his main defences into a line on Hill 281, so named by the US forces for its height, and a nearby ravine at the south-eastern end of the island. The Japanese defences included a host of tunnelled caves dug into the hill’s limestone cliffs and machine gun pits protected by sandbags. The marines reached these defences near dusk, realised they lacked sufficient daylight for a full-scale attack, and dug in for the night.

During the night of 7/8 August, the Japanese delivered five attacks on the marines' lines, beginning at 22.30. The attacks consisted of frontal charges along with individual and small group infiltration efforts towards Edson’s command post, which at times resulted in hand-to-hand combat. The Japanese temporarily broke through the marine lines and captured a machine gun, but were quickly thrown back. After taking a few more casualties, the marine lines held throughout the rest of the night. The Japanese suffered heavy losses in these attacks.

At the break of day 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 other marines killed the six Japanese with grenades. Later that morning, the marines, after landing reinforcements in the form of the 2/2^nd Marines, surrounded Hill 281 and the ravine, pounded both locations with mortar fire throughout the morning, and then assaulted the two positions, using improvised explosive charges to kill the Japanese defenders taking cover in the many caves and fighting positions throughout the hill and ravine. Significant Japanese resistance had ended by the afternoon, although a few stragglers were found and killed over the next several days. In the fighting for Tulagi, 307 Japanese and 45 US troops died, and three Japanese soldiers were taken prisoner.

The nearby islets of Gavutu and Tanambogo accommodated the Japanese seaplane base as well as 536 Japanese naval personnel of the Yokohama Air Group and 3^rd Kure Special Naval Landing Force, as well as Korean and Japanese civilian technicians and labourers of the 14^th Construction Unit. The two islets are essentially mounds of coral, each about 138 ft (42 m) high, and connected to each other by a 545-yard (500-m causeway. The hills on Gavutu and Tanambogo were called Hills 148 and 121 respectively by the Americans. The Japanese on both islets were well entrenched in bunkers and caves constructed on and in the two hills. Moreover, the two islets were mutually supportive since each was in machine gun range of the other. The US forces erroneously believed that the islets were garrisoned by only 200 naval troops and construction workers.

At 12.00 on 7 August, Gavutu was assaulted by the marines' 397-man 1^st Parachute Battalion. The assault was scheduled for 12.00 because there were not enough aircraft to provide air cover for the Guadalcanal, Tulagi and Gavutu landings at the same time. The preceding naval bombardment had damaged the seaplane ramp, forcing the naval landing craft to land their marines in a more exposed location on a nearby small beach and dock. Japanese machine gun fire began inflicting heavy casualties, killing or wounding 10% of the marines as they landed and scrambled inland in an attempt to get out of the crossfire from the two islets. Surviving marines were able to deploy a pair of machine guns to provide suppressing fire on Gavutu’s caves, allowing more marines to push inland from the landing area. Seeking cover, the marines became scattered and were quickly pinned down. Captain George Stallings, the battalion’s operations officer, directed marines to begin suppressive fire with machine guns and mortars on the Japanese machine gun emplacements on Tanambogo, and soon after this US dive-bombers dropped several bombs on Tanambogo, diminishing some of the volume of fire from that location.

After about two hours, marines reached and climbed Hill 148. Working from the top, the marines began clearing the Japanese fighting positions on the hill, most of which still remained, with explosive charges, grenades and hand-to-hand combat. From the top of the hill, the marines were also able to lay and increasing weight of suppressive fire onto Tanambogo. The marine battalion commander on Gavutu radioed Rupertus with a request for reinforcements before attempting any assault on Tanambogo.

Most of the 240 Japanese defenders on Tanambogo were aircrew and maintenance personnel of the Yokohama Air Group, and many of the maintenance personnel and construction workers were not equipped for combat. One of the few Japanese soldiers captured recounted fighting armed with only hand sickles and poles. Rupertus detached one company of marines from the 1/2^nd Marines on Florida island to bolster the assault on Tanambogo despite advice from his staff that one company was insufficient. Incorrectly believing that Tanambogo was only lightly defended, this company attempted an amphibious assault directly on Tanambogo shortly after dark on 7 August. Illuminated by fires started during a US naval bombardment of the islet, the five landing craft carrying the marines were hit by heavy fire as they approached the shore, many of the US Navy’s boat crews being killed or wounded, and three of the boats being severely damaged. Realising that his company’s position was untenable, the marines' commander ordered the remaining boats to depart with the wounded, and he and 12 men who had already landed sprinted across the causeway to find cover on Gavutu. The Japanese on Tanambogo lost 10 men killed in the day’s fighting.

Throughout the night, as the Japanese delivered 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. The 3/2^nd Marines, still embarked on ships off Guadalcanal, was notified to prepare to assault Tanambogo on 8 August. The battalion began landing on Gavutu at 10.00 on 8 August and assisted in destroying the islet’s remaining Japanese defences, an effort which had been completed by 12.00. The battalion then prepared to assault Tanambogo with covering fire provided by marines on Gavutu. 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, however, placed its shells on the correct island and shelled Tanambogo for 30 minutes. The marine assault began at 16.15, both by landing craft and from across the causeway, and, with assistance by two of the marines' M3 Stuart light tanks, began making headway against the Japanese defences. One of the tanks became stuck on a stump. Isolated from its infantry support, it was surrounded by a group of about 50 Japanese airmen, who set fire to the tank, killing two of its crew, and then severely beat the other two men of the crew before most of them were killed by marine rifle fire. The marines later counted 42 Japanese bodies around the tank’s burned-out hulk, including the corpses of the Yokohama Air Group's executive officer and several of the seaplane pilots. One of the Japanese survivors of the attack on the tank reported that 'I recall seeing my officer, Lieutenant Commander Saburo Katsuta of the Yokohama Air Group, on top of the tank. This was the last time I saw him.' The overall commander of the Japanese forces on Tanambogo was Miyazaki, who blew himself up inside his dug-out late in the afternoon of 8 August.

Throughout the day, the marines undertook a methodical destruction of the caves with explosives, obliterating most of them by 21.00. The few surviving Japanese made isolated attacks throughout the night, with hand-to-hand actions taking place. By 12.00 on 9 August, all Japanese resistance on Tanambogo had come to an end. In the battle for Gavutu and Tanambogo, 476 Japanese defenders and 70 marines or naval personnel died. Of the 20 Japanese prisoners taken during the battle, most were not actually Japanese combatants but Korean labourers.

In contrast with those on Tulagi, Gavutu and Tanambogo, the landings on Guadalcanal encountered considerably less resistance. At 09.10 on 7 August, Vandegrift and 11,000 marines came ashore on Guadalcanal between Koli Point and Lunga Point. Advancing toward Lunga Point, they encountered no resistance except for thickness of the rain forest, and halted for the night about 1,100 yards (1005 m) from the Lunga Point airfield. On the following day, again against little resistance, the marines reached the Lunga river and had secured the airfield by 16.00 on 8 August. The Japanese naval construction units had abandoned the airfield area, leaving behind food, supplies and intact construction equipment and vehicles.

During the battle, about 80 Japanese escaped from Tulagi and Gavutu-Tanambogo by swimming to Florida island where, over the next two months, they were all hunted down and killed by patrols of the marines and the British Solomon Islands Protectorate Defence Force.

The Allies quickly turned the Tulagi anchorage, one of the best natural harbours in the South Pacific, into a naval base and refuelling station. During the Guadalcanal and Solomon islands campaigns, 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 in the Guadalcanal area that could not depart by the fall of night frequently took overnight refuge in Tulagi’s harbour. Allied ships damaged in the naval battles fought between August and December in the vicinity of Guadalcanal usually anchored in Tulagi’s harbour for temporary repairs before heading to rear-area ports for permanent repairs.

Later in the campaign, Tulagi also became a base for US PT-boats that attempted to interdict 'Tokyo Express' missions by Japanese destroyers to resupply and reinforce the land forces on Guadalcanal. A seaplane base was also established on nearby Florida island. Except for some troops left to build, garrison, operate and defend the base at Tulagi, most of the marines who had assaulted Tulagi and the nearby islets were soon relocated to Guadalcanal to help defend the Lunga Point airfield, later called Henderson Field.