 On 7 August 1942 , Allied forces ( primarily United States ) landed on Guadalcanal , Tulagi , and Florida Islands in the Solomon Islands . The landings on the islands were meant to deny their use by the Japanese as bases for threatening the supply routes between the US and Australia , and to secure the islands as starting points for a campaign with the eventual goal of capturing or neutralizing the major Japanese base at Rabaul while also supporting the Allied New Guinea campaign . The landings initiated the six @-@ month @-@ long Guadalcanal campaign . 
