The new Chalfonte-Haddon Hall complex consisted of 1,000 rooms and, at the time of its completion, was the city's largest hotel by capacity. During World War II, under the command of Col. Robert C. McDonald, M.C. (November 27, 1943—June 30, 1944), Chalfonte-Haddon Hall was leased by the US Military as part of Army Air Force Basic Training Center No. 7. The forty-seven Atlantic City resort hotels taken over by the United States Military were collectively dubbed "Camp Boardwalk". The Chalfonte-Haddon Hall was merged with the adjacent Traymore Hotel and the complex was named the England General Hospital, for Lt. Col. Thomas Marcus England, who had worked with Walter Reed researching yellow fever in Cuba in 1900. The hospital opened on April 28, 1944. The last patients left the hospital in June 1946, and the Chalfonte-Haddon Hall was returned to its owners, reopening as a resort on August 1, 1946.