At
Oakland,
California, Sprague took command of the cargo ship , which was being converted into a seaplane tender in July 1940.
Tangier was commissioned on August 25, 1941, and shortly thereafter transited to Bremerton, Washington, to load torpedoes. At her homeport in
Pearl Harbor,
Hawaii,
Tangier was mated with Fleet Patrol Wing Two.
Tangier was berthed at F-10 on the northwest side of
Ford Island on the morning of December 7, 1941. She was one of the first ships in the harbor to open fire and engaged several Japanese aircraft throughout the morning.
Tangier was credited with downing three aircraft. As a result of his leadership at Pearl Harbor, Sprague was promoted to
captain on January 3, 1942. In early 1942
Tangier saw service at
New Caledonia. Sprague was assigned as air officer of
Gulf Sea Frontier,
Miami,
Florida, in June 1942. His duties involved improving defenses, keeping the sea lanes open, and countering the German
U-boats on the Southeast coast of the United States. Upon achieving his goals he was transferred in March 1943. In April 1943, Sprague was transferred to
Naval Air Center,
Seattle, Washington, where he served as commander of the base and nearby
Naval Air Station Sand Point. This duty ended abruptly when he was assigned as the commanding officer of the newly constructed fast fleet carrier in October 1943. Arriving at
Bethlehem Steel's
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. Sprague was designated as commander of Carrier Division 25 on July 23, 1944, with his flag in , replacing Rear Admiral
Gerald F. Bogan. In September 1944 his task unit supported the
Morotai landing. Sprague's greatest achievement came on October 25, 1944, when his Task Unit 77.4.3 (radio call sign Taffy III) consisting of 6
escort carriers, 3
destroyers, and 4
destroyer escorts fought off the 4
battleships, 6
heavy cruisers, 2
light cruisers, and 11 destroyers of Japanese Admiral
Takeo Kurita's vastly superior Center Force at the
Battle off Samar near
Samar Island in the
Philippines. Taken by surprise by Kurita's larger, faster ships, Sprague coolly maneuvered his force to take maximum advantage of the wind and weather while his pilots bombed and strafed the attacking ships, even making
dry runs after their ammunition ran out. He ordered his escorts to lay smoke to cover the carriers, then ordered them to counterattack with torpedoes, culminating in toe-to-toe gun duels between Taffy III's destroyers and destroyer escorts and Center Force's battleships and cruisers. Taffy III was mauled by Center Force, with four ships sunk and most of the others damaged, but Sprague succeeded in turning Kurita back, preventing him from reaching his intended target—the vulnerable invasion shipping off
Leyte Island—and sinking three of Center Force's heavy cruisers. Sprague was awarded the
Navy Cross for the leadership he displayed off Samar. On February 19, 1945, Sprague assumed command of Carrier Division 26 embarked on for the
invasion of Iwo Jima where his unit provided close air support for the Marines ashore. The next month he moved his flag back to
Fanshaw Bay for the
invasion of Okinawa. In April 1945, Sprague was given command of
Carrier Division 2, a fast carrier Task Group and moved his flag to on June 1, 1945. His task group operated against the Japanese home islands of
Kyūshū,
Honshū, and
Hokkaidō. Sprague received the notification of the end of hostilities while steaming 151 miles off the eastern coast of Honshū on August 15, 1945. Four days after the Japanese surrender, Sprague and
Ticonderoga entered
Tokyo Bay. ==Post War – Operation Crossroads and final duties==