HMS Courageous was the lead ship of the Courageous-class cruisers built for the Royal Navy during the First World War. Designed to support the Baltic Project championed by First Sea Lord John Fisher, the ship was very lightly armoured and armed with only a few heavy guns. Courageous was completed in late 1916 and spent the war patrolling the North Sea. She participated in the Second Battle of Heligoland Bight in November 1917 and was present when the German High Seas Fleet surrendered a year later.
Courageous was decommissioned after the war, then rebuilt as an aircraft carrier during the mid-1920s. She could carry 48 aircraft compared to the 36 carried by her half-sister Furious on approximately the same displacement. After recommissioning she spent most of her career operating off Great Britain and Ireland. She briefly became a training carrier, but reverted to her normal role a few months before the start of the Second World War in September 1939. Courageous was torpedoed and sunk in the opening weeks of the war, going down with more than 500 of her crew.