Briscoe went through initial shakedown exercises off San Pedro, Los Angeles in November, 1944. Then, she loaded troops and cargo at Port Hueneme, California, and steamed to Pearl Harbor, where she arrived on 13 December and reported to the Commander, Naval Surface Forces Pacific (ComPhibPac), at Pearl Harbor Naval Station, as a Transports-Assault (APA) class ship. She engaged in more training and shakedown exercises, including, "gunnery, towing, night steaming, fueling at sea, damage control, and other operational and combat procedures" preparing for the invasion of Iwo Jima.[1] In February 1945, she underwent repairs of her engineering plant missing the Battle of Iwo Jima. During her preparation for the Battle of Okinawa, she collided with the USS Osage (LSV-3). Repairs kept her grounded until 6 April 1945, when she joined the Transport Division (TransDiv) 51 and proceeded to shuttle troops and cargo between the Marshalls, Marianas, Philippines, Solomon Islands, and New Guinea, making a trip to San Francisco in May.[1]
After hostilities
On 27 August 1945, after being delayed by a typhoon, Briscoe departed the Philippines for Japan. Upon arrival, she joined the naval occupation forces and served primarily as a transport between the Philippine Islands and China. On 2 September 1945, she was present in Tokyo Bay during the Surrender of Japan formal ceremony, passing past USS Missouri (BB-63) in a convoy of Allied ships.[2] Next day, she departed from Tokyo Bay with troops who were ordered to occupy the Tateyama naval air station. After that, she carried troops from Guam to Okinawa, and later to northern China.[1]Briscoe departed the Far East 30 November 1945 and returned to the United States. During the early months of 1946, she made several voyages between the ports of California and the Pacific islands as part of the so-called Magic Carpet Fleet, returning American troops to the United States.[1]