During the Pacific War Funafuti was used as a base to prepare for the subsequent seaborn attacks on the Gilbert Islands (Kiribati) that were occupied by Japanese forces. The United States Marine Corps landed on Funafuti on 2 October 1942 and on Nanumea and Nukufetau in August 1943. The Japanese had already occupied Tarawa and other islands in what is now Kiribati, but were delayed by the losses at the Battle of the Coral Sea. The islanders assisted the American forces to build airfields on Funafuti, Nanumea and Nukufetau and to unload supplies from ships. On Funafuti the islanders shifted to the smaller islets so as to allow the American forces to build the airfield and to build naval bases and port facilities on Fongafale. A Naval Construction Battalion (Seabees) built a sea plane ramp on the lagoon side of Fongafale islet for seaplane operations by both short and long range seaplanes and a compacted coral runway was also constructed on Fongafale, with runways also constructed to create Nanumea Airfield and Nukufetau Airfield. USN Patrol Torpedo Boats (PTs) were based at Funafuti from 2 November 1942 to 11 May 1944.
For what purpose was Funafuti used during the Pacific War? 
a base