HMCS Buckingham was a River-class frigate that served with the Royal Canadian Navy during the Second World War and as a Prestonian-class frigate from 1954–1965. She was named for Buckingham, Quebec. She is considered a significant part of Canadian naval history as used for some early trials of helicopter landings on smaller escort vessels. This led to the development of the future helicopter carrying destroyers.

Buckingham was ordered 1 February 1943 as part of the 1943–1944 River-class building program. She was laid down as Royal Mount on 11 November 1943 by Davie Shipbuilding & Repairing Co. Ltd. at Lauzon and launched 28 April 1944. Her name was changed to Buckingham and she was commissioned on 2 November 1944 at Quebec City.

The River-class frigate was designed by William Reed of Smith's Dock Company of South Bank-on-Tees. Originally called a "twin-screw corvette", its purpose was to improve on the convoy escort classes in service with the Royal Navy at the time, including the Flower-class corvette. The first orders were placed by the Royal Navy in 1940 and the vessels were named for rivers in the United Kingdom, giving name to the class. In Canada they were named for towns and cities though they kept the same designation. The name "frigate" was suggested by Vice-Admiral Percy Nelles of the Royal Canadian Navy and was adopted later that year.

Improvements over the corvette design included markedly better accommodation. The twin engines gave only three more knots of speed but extended the range of the ship to nearly double that of a corvette at 7,200 nautical miles (13,300 km) at 12 knots. Among other lessons applied to the design was an armament package better designed to combat U-boats including a twin 4-inch mount forward and 12-pounder aft. 15 Canadian frigates were initially fitted with a single 4-inch gun forward but with the exception of Valleyfield, they were all eventually upgraded to the double mount. For underwater targets, the River-class frigate was equipped with a Hedgehog anti-submarine mortar and depth charge rails aft and four side-mounted throwers.

River-class frigates were the first Royal Canadian Navy warships to carry the 147B Sword horizontal fan echo sonar transmitter in addition to the regular ASDIC. This allowed the ship to maintain contact with targets even while firing unless a target was struck. Improved radar and direction-finding equipment improved the RCN's ability to find and track enemy submarines over the previous classes.

Canada originally ordered the construction of 33 frigates in October 1941. The design was too big for the shipyards on the Great Lakes so all the frigates built in Canada were built in dockyards along the west coast or along the St. Lawrence River. In all Canada ordered the construction of 60 frigates including ten for the Royal Navy that in turn transferred two to the United States Navy.

Buckingham returned to Halifax after working up at Bermuda in January 1945 and was assigned to the convoy escort group EG 28. She remained with this unit until the end of hostilities in Europe performing local escort duties for coastal convoys along the eastern coast of Canada.

On 10 May, U-889 was spotted south of Newfoundland by a RCAF airplane, steaming at 10 knots (19 km/h; 12 mph) and flying a black flag of surrender. The RCAF plane radioed to nearby Western Escort Force W-6 who intercepted the submarine an hour later. U-889 was ordered to head to Bay Bulls, Newfoundland. 24 hours later U-889 was turned over to the frigates Buckingham and Inch Arran who escorted her to Shelburne Harbour where she was boarded.