HMS Indefatigable was one of two Implacable-class aircraft carriers built for the Royal Navy (RN) during World War II. Completed in 1944, her aircraft made several attacks that year against the German battleship Tirpitz, inflicting only light damage; they also raided targets in Norway. The ship was transferred to the British Pacific Fleet (BPF) at the end of the year and attacked Japanese-controlled oil refineries in Sumatra in January 1945 before joining the American forces in March as they prepared to invade the island of Okinawa in Operation Iceberg. Indefatigable and the BPF joined the Americans in attacking the Japanese Home Islands in July and August. Following the end of hostilities she visited ports in Australia, New Zealand and South Africa.

The Implacable-class aircraft carrier consisted of two aircraft carriers built for the Royal Navy during World War II. Derived from the design of the Illustrious class, they were faster and carried more aircraft than the older ships. They were initially assigned to the Home Fleet when completed in 1944 and attacked targets in Norway as well as the German battleship Tirpitz. Subsequently, they were assigned to the British Pacific Fleet (BPF).