Amphibious Construction Battalion ONE (ACB1 or ACB-1 or PHIBCB 1 or PHIBCB One) is an amphibious construction battalion in the United States Navy based in Coronado, California. Amphibious Construction Battalion TWO is its sister unit based in Little Creek, Virginia.ACB-1 was originally commissioned at Camp Peary, Williamsburg, Virginia, 16 July 1943, as the 104th Naval Construction Battalion and was sent to Camp Endicott, Gulfport, Mississippi. During World War II CBs sent to the Pacific were attached to one of the four Amphibious Corps: I, III, and V were U.S. Marine Corps (under Admiral Nimitz, CINCPOA, Pearl Harbor) while VII Amphibious Corps was U.S. Army (under General MacArthur, SWPA, Brisbane, Australia).