In late 1940, King left the General Board to become commander-in-chief of the
Atlantic Fleet. A year later, in the aftermath of the Japanese
attack on Pearl Harbor, King was elevated to Commander in Chief,
United States Fleet, and promptly forced
Chief of Naval Operations Harold R. Stark to release his assistant, Rear Admiral
Royal E. Ingersoll, to succeed King in command of the Atlantic Fleet. To take Ingersoll's place, King suggested Stark select either Horne, who was awaiting retirement on the General Board, or Rear Admiral
Russell Willson, the
superintendent of the Naval Academy: "Take the one you want to replace Ingersoll and I will take the other as my chief of staff." Stark picked Horne, who served as assistant to the chief of naval operations from December 27, 1941, to March 25, 1942, Horne was promoted to vice admiral on March 10, 1942. During the war, Horne was actually
de facto CNO, since King was preoccupied with his COMINCH and
Joint Chiefs of Staff duties. King and Horne informally agreed that King would manage the war, leaving logistical matters to Horne and his top assistant, Rear Admiral
Lynde D. McCormick. He was awarded the
Legion of Merit for providing "astute guidance in staff planning and logistical collaboration concerned with problems of logistical supply", However, on February 11, 1944, Congressman
Carl Vinson, the chairman of the
House Naval Affairs Committee, revoked his support for Knox's proposal. Knox died in April, ending the proposal. In September 1944, King elevated his COMINCH chief of staff, Vice Admiral
Richard S. Edwards, to the newly created position of "Deputy COMINCH-Deputy CNO," which inserted Edwards above Horne in the
chain of command. Horne's unhappiness at the effective demotion resulted in a flurry of newspaper and radio criticism, which King tried to quell by issuing a press statement on October 4, 1944, that asserted "the duties now assigned to Vice Admiral Edwards do
not constitute a demotion of Vice Admiral Horne or anyone else." After the war, King was more candid. "Of course Horne would have liked to be CNO. Who wouldn't? But I am afraid he was not quite frank with me. I eased him out, finally." Horne was placed on the retired list on August 1, 1946, but remained on active duty as special assistant and head of the Board of Review for Decorations and Medals until April 1947. ==Personal life==