Following shakedown in the British West Indies, Register departed the United States East Coast on 11 March 1945 and headed via the Panama Canal for San Diego, California, where she arrived on 26 March 1945. She continued on to Pearl Harbor, Territory of Hawaii, which she reached on 3 April 1945. Training with underwater demolition teams followed and on 27 April 1945 she got underway, with 100 passengers embarked, for Ulithi Atoll. Arriving there on 13 May 1945, she departed as an escort of an Okinawa-bound convoy on 15 May 1945 for service in the Okinawa campaign.