The Lend-Lease Act was passed into law in the US in March 1941 enabling the United Kingdom to procure merchant ships, warships and munitions etc. from the US, in order to help with the war effort. This enabled the UK to commission the US to design, build and supply an escort vessel that was suitable for anti submarine warfare in deep open ocean situations, which they did in June 1941. Captain E.L. Cochrane of the American Bureau of Shipping came up with a design which was known as the British Destroyer Escort (BDE). The BDE designation was retained by the first six Destroyer Escorts transferred to the United Kingdom (BDE 1, 2, 3, 4, 12 and 46); of the initial order of 50 these were the only ones the Royal Navy received, the rest being reclassified as Destroyer Escort (DE) on 25 January 1943 and taken over by the United States Navy.[1]
Ships that were classified DE or DEG were reclassified in 1975 as FF or FFG (frigates). This affected hull numbers DE-1037 and higher as well as all DEGs.
DEG-7 through 13 The ships were redesignated FFG, a patrol frigate design would be re-designated the FFG-7 Oliver Hazard Perry class frigate.
Radar picket Destroyer Escorts (DER)
During World War II seven DEs would be converted to this role, and during the Cold War another 36 would be converted. All would be replaced by more modern radar by 1965.[5]
High Speed Transports (APD)
During World War II 94 DEs would be converted to High Speed Transports for amphibious assaults and raids; in 1969 all surviving ships would be reclassified as Fast Amphibious Transports (LPR).[6]