The landings were fiercely resisted by the Japanese Navy troops who, heavily outnumbered and outgunned by the Allied forces, fought and died almost to the last man.

On 7 December 1941, the Japanese attacked the U.S. Pacific fleet at Pearl Harbor, Hawaii, initiating a state of war between the two nations.

The initial goals of Japanese leaders in the war were to neutralize the U.S. fleet, seize possessions rich in natural resources, and establish strategic military bases to defend Japan's empire in Asia and the Pacific.

[7] Two attempts by the Japanese to extend their defensive perimeter in the south and central Pacific were thwarted in the battles of Coral Sea (May 1942) and Midway (June).

[9] As part of an operation that resulted in the Coral Sea battle, the Japanese Navy sent troops to occupy Tulagi and nearby islands in the southern Solomons.

[10] The airfield—when complete—would protect Japan's major base at Rabaul, threaten Allied supply and communication lines, and establish a staging area for possible future offensives against Fiji, New Caledonia, and Samoa (Operation FS).

[11] The Allied plan to attack the southern Solomons was conceived by U.S. Admiral Ernest King, Commander in Chief, United States Fleet.

He proposed the offensive to deny the use of the southern Solomon Islands by the Japanese as bases to threaten the supply routes between the U.S. and Australia, and to use them as starting points for a campaign with the objective of capturing or neutralizing the major Japanese base at Rabaul while also supporting the Allied New Guinea campaign, with the eventual goal of opening the way for the U.S. to retake the Philippines.

[14] Espiritu Santo in the New Hebrides was selected as the headquarters and main base for the impending offensive—codenamed Operation Watchtower—with the commencement date set for 7 August.

In command of the 3,000 U.S. Marines set to land on Tulagi and the nearby islands of Florida, Gavutu, and Tanambogo was U.S. Brigadier General William H. Rupertus on the transport ship USS Neville.

[18] Bad weather allowed the Allied expeditionary force to arrive in the vicinity of Guadalcanal unseen by the Japanese on the morning of 7 August.

The Japanese detected the radio traffic from the incoming Allied invasion force and prepared to send scout aircraft aloft at daybreak.

[21] The cruiser USS San Juan and destroyers Monssen and Buchanan bombarded planned landing sites on Tulagi and Florida Island.

The Marines, however, were able to wade the remaining 100 m (110 yd) without hindrance from the Japanese forces, who were apparently taken by surprise by the landings and had yet to begin any organized resistance.

At this time, the Japanese forces on Tulagi and Gavutu, a detachment of the 3rd Kure Special Naval Landing Force (SNLF) plus members of the Yokohama Air Group, commanded by Captain Shigetoshi Miyazaki, signaled their commander at Rabaul, Rear Admiral Sadayoshi Yamada, that they were under attack, were destroying their equipment and papers, and signed off with the message, "Enemy troop strength is overwhelming, We will defend to the last man."

Masaaki Suzuki, commander of the SNLF unit, ordered his troops into prepared defensive positions on Tulagi and Gavutu.

The Japanese defenses included dozens of tunneled caves dug into the hill's limestone cliffs and machinegun pits protected by sandbags.

Later that morning, the Marines, after landing reinforcements from 2nd Battalion, 2nd Marines (2/2), 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.

The assault was scheduled for noon because there were not enough aircraft to provide air cover for the Guadalcanal, Tulagi, and Gavutu landings at the same time.

Japanese machine gun fire began inflicting heavy casualties, killing or wounding one in ten of the landing Marines as they scrambled inland in an attempt to get out of the crossfire coming from the two islets.

Shortly thereafter, American dive bombers dropped several bombs on Tanambogo, diminishing some of the volume of fire from that location.

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.

[43] Throughout the night, as the Japanese staged 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 Marines later counted 42 Japanese bodies around the burned-out hulk of the tank, including the corpses of the Yokohama executive officer and several of the seaplane pilots.

[46] The overall commander of troops on Tanambogo was Captain (naval rank) Shigetoshi Miyazaki who blew himself up inside his dugout on the late afternoon of 8 August.

[52] The Allies quickly turned the Tulagi anchorage, one of the finest natural harbors in the South Pacific, into a naval base and refueling station.

[53] Later in the campaign, Tulagi also became a base for U.S. PT boats that attempted to interdict "Tokyo Express" missions by the Japanese to resupply and reinforce their forces on Guadalcanal.