The first two ships of the class, Courageous and Glorious, spent the First World War on North Sea patrols, climaxing in the Second Battle of Heligoland Bight in November 1917.
Their half-sister Furious was designed with a pair of 18-inch (457 mm) guns—as opposed to four 15-inch (381 mm)—but was modified while being built to hold a flying-off deck and hangar in lieu of her forward turret and barbette.
She made some patrols in the North Sea before her rear turret was removed and another flight deck added.
Her aircraft attacked Zeppelin sheds during the Tondern raid in July 1918.

All three ships were reduced to reserve after the war.
The Washington Naval Treaty of 1922 limited the signatory nations to a set amount of capital ship tonnage; all ships in excess of this figure had to be scrapped.
Up to 66,000 long tons (67,000 t) of existing ships could be converted into aircraft carriers, and the Royal Navy decided to use the Courageous-class ships due to their high speed.
Each ship was reconstructed with a flight deck during the 1920s.
The first two ships of the class, Courageous and Glorious, spent the First World War on North Sea patrols, climaxing in the Second Battle of Heligoland Bight in November 1917. Their half-sister Furious was designed with a pair of 18-inch (457 mm) guns—as opposed to four 15-inch (381 mm)—but was modified while being built to hold a flying-off deck and hangar in lieu of her forward turret and barbette. She made some patrols in the North Sea before her rear turret was removed and another flight deck added. Her aircraft attacked Zeppelin sheds during the Tondern raid in July 1918.
All three ships were reduced to reserve after the war. The Washington Naval Treaty of 1922 limited the signatory nations to a set amount of capital ship tonnage; all ships in excess of this figure had to be scrapped. Up to 66,000 long tons (67,000 t) of existing ships could be converted into aircraft carriers, and the Royal Navy decided to use the Courageous-class ships due to their high speed. Each ship was reconstructed with a flight deck during the 1920s.
Courageous-class aircraft carrier