Stark graduated from the Naval War College in 1924 and then served as an aide to the secretary of the navy from 1930 to 1933. Promoted to rear admiral in November 1934, he was chief of the Bureau of Ordnance from 1934 to 1937. After his promoted to vice admiral, he commanded all cruisers in the Battle Force in 1938 and 1939). During these years, Stark was a staunch proponent of naval preparedness.
In August 1939, one month before World War II began in Europe, President Franklin D. Roosevelt named Stark chief of naval operations as a full admiral. Stark, who shared Roosevelt's profoundly interventionist outlook, immediately launched an expansion program designed to make the U.S. Navy the world's largest naval force. His memorandum Plan D (Dog), prepared for Roosevelt in November 1940, delineated what became the fundamental U.S. wartime strategy—that Germany, the greatest threat to the United States, must be defeated first.
Convinced that Britain's survival was essential to U.S. national security, in early 1941 Stark proposed and held staff talks with a high-level British delegation. The resulting ABC-1 (America-Britain-Canada) Rainbow 5 strategic agreement, much of which Stark drafted, became the basis of wartime Anglo-American cooperation. Stark constantly urged Roosevelt to do more to assist Britain, and, by autumn 1941, American naval forces were effectively at war with Germany in the Battle of the Atlantic.
Although Stark attempted to improve Pacific fortifications and naval strength, he opposed measures (such as an oil embargo) that might provoke forceful Japanese responses. Like other American military and civilian officials, he failed to interpret correctly or transmit to Admiral Husband Edward Kimmel, U.S. commander in chief of the Pacific Fleet, deciphered cable traffic indicating Japan might attack America's Hawaiian Pearl Harbor naval base. One investigation later faulted him for this misjudgment.
Shortly after the Japanese attack on Pearl Harbor, Roosevelt replaced Stark as commander of U.S. naval forces with Admiral Ernest J. King. In March 1942, Roosevelt dispatched Stark to Europe as commander of U.S. naval forces in that theater. Stark performed valuable wartime liaison functions between London and Washington, established and later dismantled certain American naval bases in Europe, directed logistical support for U.S. naval forces, and served as Washington's unofficial envoy to Free French leader General Charles de Gaulle. Stark retired from active duty in 1946. He died in Washington, D.C., on 20 August 1972.
Cowman, Ian. Dominion or Decline: Anglo-American Naval Relations in the Pacific, 1937–1941. Washington, DC: Berg, 1996.; Reynolds, Clark G. Famous American Admirals. New York: Van Nostrand Reinhold, 1978.; Simpson, B. Mitchell, III. Admiral Harold R. Stark: Architect of Victory, 1939–1945. Columbia: University of South Carolina Press, 1989.; Stoler, Mark A. Allies and Adversaries: The Joint Chiefs of Staff, the Grand Alliance, and U.S. Strategy in World War II. Chapel Hill: University of North Carolina Press, 2000.