Arriving at Bethlehem Steel Company Fore River Yard near Boston, Massachusetts, Sprague took command of "Wasp" where she was commissioned on November 24, 1943. The carrier was quickly sent to the Pacific, where she joined the war against the Japanese. Her first combat missions were to destroy enemy aircraft, installations, and surface craft on Marcus and Wake Islands in May 1944. In June 1944 "Wasp" participated in the invasion of Saipan and the Battle of the Philippine Sea. On July 9, 1944, shortly before leaving "Wasp", Sprague was promoted to rear admiral at age 48.