US Navy Vice Admiral. After graduating from the University of Minnesota in 1905 he entered the US Naval Academy at Annapolis, Maryland in June 1906, graduating four years later. He then performed consecutive two year tours at sea, first on the USS Iowa, the Navy transport ship USS Prairie, and the battleship USS Florida, and participated in naval operations at Veracruz, Mexico. In 1917, when the US entered World War I, he performed duty as a gunnery officer on the Navy transports DeKalb and America, and the USS Frederick. In 1919 he was assigned to Charles Town, West Virginia for two years her he was an ordinance inspector at the Navy's Armor and Projectile Plant. He then returned to sea as the executive officer of the Navy transport Hancock and light cruiser Birmingham, and then was the commander of the Navy destroyer Marcus for a year before being reassigned as an ordinance inspector at Pittsburgh, Pennsylvania. In August 1924 he was assigned to the New York Naval Shipyard in Brooklyn, New York and his expertise in ordinance won him the position of gunnery officer on the staff of the Commander, Destroyer Squadrons, Asiatic Fleet, Philippines, in late 1925. In July 1927 he was assigned the commander of the Navy destroyer USS Paul Jones but left the following year to become an instructor at the US Naval Academy in the Department of Navigation. In 1931 he returned to sea, serving as a navigator on the Navy battleship USS Idaho, followed by a tour on the Navy cruiser USS Pensacola, and then was stationed in the Panama Canal Zone, prior to attending the Naval War College at Newport, Rhode Island. In June 1936 he became the executive officer of the Navy battleship USS Mississippi and two years later he became the Professor of Naval Science and Tactics at Tulane University in New Orleans, Louisiana. In July 1940 he was promoted to captain and became the commander of Navy Destroyer Squadron 2 in the Atlantic and after the US entered World War II, he was assigned to Vice Admiral William F. Halsey' staff and returned to the USS Mississippi as commander, which had been seriously damaged by the Japanese surprise attack on Pearl Harbor on December 7, 1941. In July 1942 he was promoted to rear admiral and assumed administrative command of all Pacific Fleet destroyers. In December of that year Halsey gave him the additional duty of commanding Task Force 67 which had been badly mauled in the recent Battle of Tassafaronga at Guadalcanal. He took a leading role in the Solomon Islands Campaign, commanding the bombardment of the Japanese airfield at Munda in January 1943, which is long considered a textbook operation. Afterwards, as commander of Cruiser Division 9 (January 1943-October 1944), he commanded three cruisers and five destroyers that escorted the U.S. invasion force to New Georgia. In July 1943 he fought in the Battle of Kula Gulf, for which he was awarded the Navy Cross. In the same month he also participated in the Battle of Kolombangara. Both actions were against the "Tokyo Express," the Japanese destroyers that ran resupply missions to Japanese garrisons in the Solomon Islands. During these battles several of his ships (including light cruiser USS Helena) were sunk, and several ships were damaged (including his flagship, light cruiser USS Honolulu). He continued to see action in the Marianas, Guam, Leyte Gulf, and Peleliu , where he conducted shore bombardments during these island invasions. In October 1944, during the invasion of the Philippines, his flagship was seriously damaged by an aerial torpedo. After returning to Pearl Harbor for repairs, he became Commander, Cruisers and Destroyers, Pacific Fleet, serving in that position until July 1945. In August 1945 he became commander of the Fifth Naval District, Norfolk Navy Yard, Norfolk, Virginia, serving in that position until his retirement in December 1948, at the rank of vice admiral, with 38 years of active military service. In addition to the Navy Cross, he was also awarded the Distinguished Service Medal and the Legion of Merit (2 oak leaf clusters). The Navy destroyer escort Ainsworth is named in his honor.