The Canadian Patrol Frigate Project (CPFP) was a procurement project undertaken by the Department of National Defence of Canada beginning in 1975 to find a replacement for the 20 combined ships of the Annapolis, Mackenzie, Restigouche, and St. Laurent classes of destroyer escorts. The CPFP was considered a core effort in the fleet modernization of Canada in the 1980s. Facing several contract hurdles, the construction program got underway in 1987. The CPFP became known as the Halifax-class frigate upon the construction of the ships. The Halifax class replaced the destroyer escort classes in the 1990s and remains a core element of the fleet.