) was the United States Navy
mid-20th-century classification for a 20-knot (23 mph) warship
designed with endurance to escort mid-ocean convoys
of merchant marine
were designed for a similar role in the Imperial Japanese Navy
The Royal Navy
and Commonwealth forces identified such warships as frigates
, and that classification was widely accepted when the United States redesignated destroyer escorts as frigates (FF) in 1975.