The USMC headquarters moved to the Navy Annex in November 1941. A Headquarters and Service Company was organized on March 1, 1942, and a Women Marine Company (part of the United States Marine Corps Women's Reserve) organized as part of the headquarters unit on April 1, 1943. To house both companies, the Marine Corps began acquiring, through purchase, easement, eminent domain, and other means, property to the west and northwest of the Navy Annex Building. This included most of the Syphax land, except for that already purchased by Abbey Mausoleum. Henderson Hall was built on this property in September 1943 to house both companies. All told, were acquired, and athletic fields, a bowling alley, chapel, firing range, gas station, gym, hobby shop, officers' and enlisted men's clubs, post exchange, post office, radio station, supply depot, and swimming pool were all built on the site.