HMS Crusader was a C-class destroyer built for the Royal Navy in the early 1930s. She saw service in the Home and Mediterranean Fleets and spent six months during the Spanish Civil War in late 1936 in Spanish waters, enforcing the arms blockade imposed by Britain and France on both sides of the conflict. Crusader was sold to the Royal Canadian Navy (RCN) in 1938 and renamed HMCS Ottawa. She was initially deployed on the Canadian Pacific Coast before World War II, but was transferred to the Atlantic three months after the war began. She served as a convoy escort during the battle of the Atlantic until sunk by the German submarine U-91 on 14 September 1942. Together with a British destroyer, she sank an Italian submarine in the North Atlantic in November 1941.

The C and D class was a group of 14 destroyers built for the Royal Navy in the early 1930s. As in previous years, it was originally intended to order a complete flotilla comprising eight destroyers—plus a flotilla leader as the ninth unit—in each year. However, only four ships—plus a leader—were ordered under the 1929–1930 Programme as the C class. The other four ships planned for the C class were never ordered as an economy measure and disarmament gesture by the Labour government of Ramsay MacDonald. A complete flotilla—the 'D' class—was ordered under the 1930–1931 Programme.