HMS Ajax was a King George V class battleship (one of four ships of the class), built at Scotts' shipyard at Greenock on the River Clyde. She was completed in 1913 and saw action at the Battle of Jutland in 1916 and in the Mediterranean and Black Seas in 1919, before being sold for scrap in 1924.
Ajax served on the America and West Indies Station from completion, then part of South American Division on the outbreak of the Second World War in September 1939. Operating off the River Plate, she intercepted the German merchantmen Carl Fritzen, Olinda, and Ussukuma. She was the flagship of Commodore Henry Harwood's Force G during the hunt for the Admiral Graf Spee. Ajax was hit seven times during the Battle of the River Plate on 13 December 1939.
Under repair until July 1940, she then moved to the Mediterranean. On October 11/12 1940 she engaged Italian forces, sinking the torpedo boats Airone and Ariel, and badly damaging the destroyer Artigliere, which was later sunk. Ajax participated in the Battle of Cape Matapan and the evacuation from Crete, removing the last troops on 29 April 1941. She was hit by bombs from Ju87's on 21 May, covered Syrian operations in June, and joined Force K at Malta in November 1941, but was withdrawn February 1942.
She was refitted in England, May-October 1942, then returned to the Mediterranean where she was damaged by bombs again, necessitating repairs in New York between March and October 1943. Ajax returned to the Mediterranean again, then to Normandy with Force K at Gold Beach for the D-Day landings, and at landings in southern France. Ajax operated in the Aegean during the reoccupation of Athens and the communist uprising in Greece.
Laid up postwar, she was broken up in November 1949.
The Town of Ajax, in Ontario, Canada, was named after the cruiser following the Battle of the River Plate. The town has streets named after members of the ship's company. For example, Harwood Avenue is the town's main north-south street.