 Shortly before the United States' entry into World War II, a 2,600 acre (11 km²) tract of land was purchased in western Duval County and construction began on the "U.S.Naval Auxiliary Air Station, Cecil Field" (NAAS Cecil Field).The base got its start in June 1941 as an outlying field of NAS Jacksonville, and operations were accelerated just 11 days after the Japanese Attack on Pearl Harbor.