of Naval Science and Tactics at Tulane University in New Orleans, Louisiana. World War II World War II in Europe was almost a year old when he took command of Destroyer Squadron 2 (DesRon 2) on July 22, 1940, and the United States had just entered that conflict when he returned to Mississippi as her commanding officer on December 19, 1941. Ainsworth promptly took that veteran battleship to the Pacific to strengthen the Navy's surface force in that ocean which had been seriously weakened by the Japanese surprise attack on Pearl Harbor. On July 4, 1942, Ainsworth took administrative command of all Pacific Fleet destroyers (ComDesPac). On December 10 of that year, Admiral William F. Halsey gave him the additional duty of commanding Task Force 67 (TF 67) which had been badly mauled in the recent Battle of Tassafaronga; and, under his leadership that cruiser-destroyer force was soon winning renown as the "Ainsworth Express" for its fierce fighting in support of the final American drive to push Japanese troops off Guadalcanal. Its bombardment of the new Japanese air base at Munda on the island of New Georgia would be, in the words of naval historian, Samuel Eliot Morison, "... long regarded as a model...." Transferred to command of TF 18 and Cruiser Division 9 (CruDiv 9), Ainsworth continued his success during a prolonged series of runs up the long, narrow body of water between the central Solomon Islands which American bluejackets had nicknamed "the Slot". These operations parried the thrusts by Japanese warships challenging Allied control of the area. At the end of June, the tempo of American fighting in the southwestern Pacific picked up since the Navy had finally managed to assemble enough amphibious shipping in that theatre to resume the offensive. On the night of July 4–5, TF 18 moved up "the Slot" and bombarded Japanese positions at Vila on Kolombangara and at Baiko on New Georgia. The next afternoon, while Ainsworth's force was retiring from this action, word reached him that a large Japanese force was heading toward "the Slot". In an effort to meet and check this new threat, his warships again reversed course and headed toward the enemy. Ainsworth's "... outstanding leadership, brilliant tactics and courageous conduct ..." in the ensuing battle of Kula Gulf won him a Navy Cross. He also received the Distinguished Service Medal for his overall performance in the Southwest Pacific.