The landing at guadalcanal was the first american of world war ii.

The landing at Guadalcanal was the first major offensive of World War II by the United States.

This landing launched a series of attacks lead by the US between August 1942 and February 1943. The goal of the Guadalcanal Campaign was to ensure that the Japanese did not interrupt the communication between the United States and their Allies (aka Australia and New Zealand). They would also use this base as a means to neutralize Japan's military forces at Rabaul.

Answer might be b i think