World War I he served as gunnery officer of until September 1917, after which he assumed command of . He was assigned to in February 1918. He took command of the destroyer in May 1918, receiving the Navy Cross for leading her through "important, exacting and hazardous duty". From October 1918 to February 1919, he assisted in fitting out the destroyer , but was detached before her commissioning. He then had similar duty with , and upon her commissioning on March 8, 1919, assumed command. He was relieved of that command in April 1919. Returning to Washington, he was head of the Detail Section, Enlisted Personnel Division in the Bureau of Navigation until September 1922. Interwar service He returned to the Asiatic Station, having consecutive command of , , , and the submarine base at Cavite. Returning to the United States, he served at the Washington Navy Yards from March 1925 to 1927; became executive officer of the battleship ; and completed the Senior Course at the Naval War College, Newport in 1929–30, followed immediately by the Army War College in Washington, D.C., 1930–31, in preparation for strategic leadership responsibilities. Fletcher became chief of staff to the Commander in Chief, US Asiatic Fleet in August 1931. In the summer of 1933, he was transferred to the Office of the Chief of Naval Operations. Following this assignment he had duty from November 1933 to May 1936, as aide to the Secretary of the Navy, the Honorable Claude A. Swanson. He assumed command of the battleship , flagship of Battleship Division Three, in June 1936. In December 1937, he became a member of the Naval Examining Board, and became Assistant Chief of Bureau of Navigation in June 1938. In November 1939, Fletcher was promoted to Flag Rank, Rear Admiral, and Commander Cruiser Division Three (Light Cruisers). In June 1940, RAdm Fletcher was placed in command of Cruiser Division Six (Heavy Cruisers), the position he held on December 7, 1941. RAdm Fletcher was scheduled to become Commander, Cruisers, Scouting Force, in administrative charge of all Heavy Cruisers but the events of December 7 changed those plans.> World War II Pearl Harbor RADM Fletcher was serving as Commander Cruiser Division Six and at sea when the Japanese attacked the Naval Base at Pearl Harbor on December 7, 1941. Admiral Kimmel, CinC PAC, thought enough of RADM Fletcher to put his name third on a