In the 1930s, several series of modern sloops were built in the United Kingdom to replace the Flower-class escorts that were in extreme demand. The lead ship entered service in 1940. During World War II, she escorted convoys, hunted submarines, and covered the landing of Allied forces in North Africa. In 1949, the ship was damaged by Chinese artillery during the Amethyst Incident. Her last campaign was in the Korean War, where Black Swan battled North Korean torpedo boats during the Battle of Chumonchin Chan.