Sydney was the first of three conventional aircraft carriers to serve in the RAN, and operated as the navy's flagship during the early part of her career. From late 1951 to early 1952, she operated off the coast of Korea during the Korean War, making her the first carrier owned by a Commonwealth Dominion, and the only carrier in the RAN, to see wartime service. Retasked as a training vessel following the 1955 arrival of her modernised sister ship, HMAS Melbourne, Sydney remained in service until 1958, when she was placed in reserve as surplus to requirements.