In an attempt to strengthen Cause_change_of_strength their defensive Defending position in the South Pacific , the Japanese decided Deciding to invade Attack and occupy Control Port Moresby ( in New Guinea ) and Tulagi ( in the southeastern Solomon Islands ) .

On 3–4 May , Japanese forces successfully invaded Attack and occupied Control Tulagi , although several of their supporting Supporting warships were sunk or damaged Damaging in surprise attacks Attack by aircraft from the U.S. fleet carrier .

The invasion Attack of Tulagi , on 3–4 May 1942 , was part of Operation Military_operation `` Mo '' , the Empire of Japan 's strategy in the South Pacific and South West Pacific Area in 1942 .

The plan called Request for Imperial Japanese Navy troops to capture Conquering Tulagi and nearby islands in the British Solomon Islands Protectorate .

The occupation Control of Tulagi by the Japanese was intended to cover Hiding_objects the flank of and provide Supply reconnaissance support Supporting for Japanese forces that were advancing Self_motion on Port Moresby in New Guinea , provide Supply greater defensive depth for the major Japanese base at Rabaul , and serve Assistance as a base for Japanese forces to threaten and interdict the supply and communication routes between the United States and Australia and New Zealand .

Without the means to effectively resist Defending the Japanese offensive in the Solomons , the British Resident Commissioner of the Solomon Islands protectorate and the few Australian troops assigned Choosing to defend Defending Tulagi evacuated the island just before the Japanese forces arrived on 3 May .

The next day , however , a U.S. aircraft carrier task force en route to resist Defending the Japanese forces advancing on Port Moresby ( later taking part in the Battle of the Coral Sea ) struck Attack the Japanese Tulagi landing force in an air attack , destroying Destroying or damaging Damaging several of the Japanese ships and aircraft involved in the landing operation .

Nevertheless , the Japanese troops successfully occupied Control Tulagi and began Process_start the construction Building of a small naval base .

The Japanese activities on Tulagi and Guadalcanal were observed Perception_active by Allied reconnaissance aircraft , as well as by Australian coastwatcher personnel stationed in the area .

Because these activities threatened Warning the Allied supply and communication lines in the South Pacific , Allied forces counter-attacked Attack with landings of their own on Guadalcanal and Tulagi on 7 August 1942 , initiating Process_start the critical Guadalcanal campaign and a series of combined arms battles between Allied and Japanese forces that , along with the New Guinea campaign , decided the course of the war in the South Pacific .