Gatacre was promoted to the rank of commander in December 1941, before returning to Australia in April 1942. He was appointed upon his return as a staff officer and intelligence and operations aboard , seeing multiple actions in the South West Pacific theatre over the next two years, including the battles of Savo Island and the Eastern Solomons, as well as the amphibious landings along the Papua New Guinea coastline. For his actions in the Eastern Solomons, he was awarded a Bar to his Distinguished Service Cross. In August 1944, he was posted to a shore position in Melbourne, tasked with post-war planning. He held this position for a year, before being placed aboard as the ship's commanding officer in August 1945. Following the war, the ship assisted with the Commonwealth Occupation of Japan.