Naval Advance Base Espiritu Santo or Naval Base Espiritu Santo, most often just called Espiritu Santo, was a major advance Naval base that the U.S. Navy Seabees built during World War II to support the allied effort in the Pacific. The base was located on the island Espiritu Santo in the New Hebrides, now Vanuatu in the South Pacific. The base also supported the U.S. Army and Army Air Corps, U.S. Coast Guard, and US Marine Corps. It was the first large advance base built in the Pacific. By the end of the war it had become the second-largest base in the theater. To keep ships tactically available there was a demand for bases that could repair and resupply the fleet at advance locations, rather than return them to the United States. Prior to December 7th, Pearl Harbor was the U.S. fleet's la