By the end of 1919, "Centurion" had been transferred to the Mediterranean Fleet. Although she spent much of her time in reserve, she had a peripheral role in the Allied intervention in the Russian Civil War. After her return home in 1924, the ship became the flagship of the Reserve Fleet. In 1926 "Centurion" was converted into a target ship and participated in trials evaluating the effectiveness of aerial bombing in addition to her normal duties. During the Second World War, the ship was rearmed with light weapons and was converted into a blockship in 1941. When that operation was cancelled, she was then modified into a decoy with dummy gun turrets in an attempt to fool the Axis powers. "Centurion" was sent to the Mediterranean in 1942 to escort a convoy to Malta, although the Italians quickly figured out the deception. The ship was deliberately sunk during the Invasion of Normandy in 1944 to form a breakwater.