Destroyer escort A destroyer escort ( DE ) is the classification for a smaller , lightly armed warship designed to be used to escort convoys of merchant marine ships , primarily of the United States Merchant Marine in World War II . Slower and less expensive than a fleet destroyer , destroy escorts were employed primarily for anti - submarine warfare , but also provided some protection against aircraft and smaller attack vessels . The US built roughly 457 destroyer escorts spread out over 8 classes . The Royal Navy deployed destroyer escorts of the " Evarts " subclass and of the " Buckley " subclass ( with the torpedo tubes removed ) and designating them as Captain - class frigates . The Royal Navy and Commonwealth forces ' frigates had a similar role to American destroyer escorts . Although destroyer escorts lacked the arms , armor and speed to attack fast armored cruisers and battleships , at the Battle off Samar , the task group Taffy 3 of escort carriers , destroyers and destroyer escorts were attacked by a superior Japanese fleet led by the giant battleship " Yamato " . The " Butler " - class destroyer escort " Samuel B . Roberts " became known as " the destroyer escort that fought like a battleship " as it inflicted damage from torpedoes and gunfire on much larger cruisers , and was an instrumental part of a small task force of light ships forcing a far superior enemy fleet to turn back . Origins . The Lend - lease Act was passed into law in the USA in March 1941 enabling the United Kingdom to procure merchant ships , warships , munitions and other materiel from the USA , in order to help with the war effort . This enabled the UK to commission the USA 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 January 25 , 1943 and taken over by the United States Navy . When the United States entered the war , and found they also required an anti - submarine warfare ship and that the destroyer escort fitted their needs perfectly , a system of rationing was put in place whereby out of every five destroyer escorts completed , four would be allocated to the U . S . Navy and one to the Royal Navy . General description . Full size destroyer s must be able to keep up with and exceed the speed of fast capital ship s such as fleet carriers and cruisers , typically needing better than 25 - 35 knot speeds ( dependent upon the era and navy ) and carrying torpedo es and a smaller caliber of cannon to use against enemy ships , as well as anti - submarine detection equipment and weapons . A destroyer escort only needed to be able to maneuver relative to a slow convoy ( which in WW II would travel at 10 to 12 knots ) , defend against aircraft , detect , pursue and attack submarines . These lower requirements greatly reduce the size , cost , and crew required for the destroyer escort . While fleet destroyers were more effective for anti - submarine warfare , the destroyer escort outweighed this by being able to be built faster and cheaper . Destroyer escorts were also considerably more seaworthy than corvette s . As an alternative to steam turbine propulsion found in full size destroyers and larger warships , many US destroyer escorts of the WWII period had diesel - electric or turbo - electric drive , in which the engine rooms functioned as power stations supplying current to electric motors sited close to the propellers . Electric drive was selected because it does not need gearboxes ( which were heavily in demand for the fast fleet destroyers ) to adjust engine speed to the much lower optimum speed for the propellers . The current from the engine room can be used equally well for other purposes , and post - WWII many destroyer escorts were recycled as floating power stations for coastal cities in Latin America under programs funded by the World Bank . Destroyer escorts were also useful for coastal anti - submarine and radar picket ship duty . Some 95 destroyer escorts were converted by the US to High - speed transport s ( APDs ) . This involved adding an extra deck which allowed space for about 10 officers and 150 men . Two large davits were also installed , one on either side of the ship from which landing craft ( LCVP ) could be launched . The modern Littoral Combat Ship also adds transport and boat launching capabilities to a ship smaller than a destroyer . Battle off Samar . Destroyer escorts were not meant to fight against cruisers and battleships , but that is what happened in the Battle off Samar , which was part of the Battle of Leyte Gulf , 23 – 26 October 1944 . While Admiral Halsey ' s main force of US carriers and battleships was pursuing the Japanese decoy carrier force , the task of guarding the landing ships and troops fell to escort carriers , destroyers and destroyer escorts . While the escort carriers launched their planes , the Butler - class destroyer escort ship " Samuel B . Roberts " of task group Taffy 3 joined other outgunned destroyers in a counter - attack against Admiral Kurita ' s powerful force of Japanese cruisers and battleships , including the " Yamato " . With no armor , only two 5 - inch guns and 3 Mark - 15 torpedoes capable of punching a hole in enemy hulls , her crew lacked the weapons and training in tactics to compete with the much larger heavy cruiser " Chokai " . The " Roberts " dodged shellfire to fire a salvo of 3 torpedoes which struck the cruiser . The battle continued for an hour , and the " Roberts " fired over 600 5 - inch shells , and hit the upper works with 40 mm Bofors and 20 mm anti - aircraft guns at close range . " Chikuma " ' s bridge was set afire and the number 3 gun turret was disabled . " Chikuma " scored two direct hits on the " Roberts " , which soon sank with 89 of her crew . After the battle the " Roberts " became known as " the destroyer escort that fought like a battleship " . The " Roberts " was an instrumental part of a small task force of light ships that forced a much larger armoured battle force to turn away from American landing forces in Leyte Gulf , though at a high cost . Postwar U . S . ship reclassification . After World War II United States Navy destroyer escorts were referred to as ocean escort s , but retained the hull classification symbol DE . However other navies , most notably those of NATO countries and the USSR , followed different naming conventions for this type of ship which resulted in some confusion . In order to remedy this problem the 1975 ship reclassification reclassified ocean escorts ( and by extension , destroyer escorts ) as frigate s ( FF ) . This brought the USN ' s nomenclature more in line with NATO , and made it easier to compare ship types with the Soviet Union ( see Cruiser Gap ) . As of 2006 there are no plans for future frigates for the US Navy . The DDG Zumwalt and the Littoral Combat Ship ( LCS ) are the main ship types planned in this area . One major problem with ship classification is whether to base it on a ship ' s role ( such as escort or air defense ) , or on its size ( such as displacement ) . One example of this ambiguity are the " Ticonderoga " - class air defense ships , which are classified as cruiser s even though they use the same hull as the " Spruance " - class destroyers . " Captain " class frigates of the Royal Navy . The Captain class was a designation given to 78 frigate s of the Royal Navy , constructed in the United States of America , launched in 1942 – 1943 and delivered to the United Kingdom under the provisions of the Lend - Lease agreement ( under which the United States of America supplied the United Kingdom and other Allied nations with materiel between 1941 and 1945 ) , they were drawn from two sub - classes of the destroyer escort ( originally British destroyer escort ) classification : 32 from the " Evarts " sub - class and 46 from the " Buckley " sub - class . Upon reaching the UK the ships were substantially modified by the Royal Navy , making them distinct from the US Navy destroyer escort ships . Captain - class frigates acted in the roles of convoy escorts , anti - submarine warfare vessels , coastal forces control frigates and headquarters ships for the Normandy landings . During the course of World War II this class participated in the sinking of at least 34 German submarines and a number of other hostile craft with 15 of the 78 Captain - class frigates being either sunk or written - off as a constructive total loss . In the post - war period , all of the surviving Captain - class frigates except one ( HMS " Hotham " ) were returned to the US Navy before the end of 1947 in order to reduce the amount payable under the provisions of the Lend - Lease agreement ; the last Captain - class frigate was returned to United States custody in March 1956 . Free French . Six " Cannon " class Destroyer Escorts were built for the Free French Navy . Although initially transferred under the Lend - lease Act these ships were permanently transferred under the Mutual Defense Assistance Program . Mutual Defense Assistance Program - Post WWII . Under the Mutual Defense Assistance Program ( MDAP ) the Destroyer Escorts leased to the Free French were permanently transferred to the French Navy . In addition the following navies also acquired Destroyer Escorts : Royal Navy . DE - 574