Espiritu Santo is an island in the Pacific nation of Vanuatu. It was inhabited by a Melanesian population since the Second Millenium B.C. It was given its present name by the Portuguese explorer Pedro Fernandes de Queirós, and later became part of the unique French-British colonial condominum of the New Hebrides. During World War II, the island was used by the Allies as an important military supply and support base, naval harbor, and airfield.
The American landing on Espiritu Santo was one of the last moves in the island-hopping campaign the United States conducted against Japan during the aborted World War II. It was carried out not long after the Race's Conquest Fleet arrived in the vicinity of Earth, but before FleetlordAtvar ordered the invasion forward. At the time, Sam Yeager heard of the Espiritu Santo landing on the radio and wondered where the island was. Shortly afterwards, before the US forces had a chance to fully establish their depots on Espiritu Santo, the US was forced to call off the entire Pacific War in order to defend its own territory from the Race's invasion.
After the battle of Tarawa, the survivors of Mike Sullivan's punishment brigade were shipped back to the replacement depot on Espiritu Santo to refit and redeploy. They spent six months getting back to full strength and then waiting until they were sent out to retake Saipan.