# Destroyer escort

Destroyer escort (DE) was the United States Navy mid-20th-century classification for a 20-knot (37 km/h; 23 mph) warship designed with the endurance necessary to escort mid-ocean convoys of merchant marine ships.
Development of the destroyer escort was promoted by the British need in World War II for anti-submarine ships that could operate in open oceans at speeds of up to 20 knots. These "British Destroyer Escort"s were designed by the US for mass-production under Lend Lease as a less expensive alternative to fleet destroyers.
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. From circa 1954 until 1975 new-build US Navy ships designated as destroyer escorts (DE) were called ocean escorts. Similar types of warships in other navies of the time included the 46 diesel powered Kaibōkan of the Imperial Japanese Navy, 10 Kriegsmarine F-class escort ships, and the two Amiral Murgescu-class vessels of the Romanian Navy.
Postwar destroyer escorts and frigates were larger than those produced during wartime, with increased anti-aircraft capability, but remained smaller and slower than postwar destroyers. As Cold War destroyer escorts became as large as wartime destroyers, the United States Navy converted some of their World War II destroyers to escort destroyers (DDE).

## General description

Full-sized destroyers must be able to steam as fast or faster than cruisers and fast capital ships such as fleet carriers. This typically requires a speed of 25–35 knots (46–65 km/h) (dependent upon the era and navy). They must carry torpedoes and a smaller caliber of naval guns to use against enemy ships, anti-aircraft guns, and antisubmarine detection equipment and weapons. While these requirements made the destroyer a fast all-around combatant, this made them too valuable to be relegated to convoy escort duties.
A destroyer escort needed only to be able to maneuver relative to a slow convoy (which in World War II would travel at 10 to 12 knots (19 to 22 km/h)), be able to defend against aircraft, and detect, pursue, and attack submarines. These lower requirements greatly reduce the size, cost, and crew required for the destroyer escort. Destroyer escorts were optimized for antisubmarine warfare, having a tighter turning radius and more specialized armament (such as the forward-firing Hedgehog mortar) than fleet destroyers. The slower speed of destroyer escorts was not a liability in this context as sonar was useless at speeds over 20 knots (37 km/h).
As an alternative to geared steam-turbine propulsion found in sloops of similar purpose, size and speed (as well as full-sized destroyers and larger warships), many US destroyer escorts of the World War II period had diesel-electric or turboelectric 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 (produced on special precise machining tooling available in limited quantities, they were heavily in demand for the fast fleet destroyers) to adjust engine speed to the much lower optimal speed for the propellers. The current from the engine room can be used equally well for other purposes, and after the war, many destroyer escorts were re-used as floating power stations for coastal cities in Latin America under programs funded by the World Bank.. Edsall-class ships were the exception to this and they used a geared diesel engine to drive the propellers directly. John C. Butlers used the typical boiler and geared turbine propulsion system.
Destroyer escorts were also useful for coastal antisubmarine and radar picket ship duty. During World War II, seven destroyer escorts (DEs) were converted to radar picket destroyer escorts (DERs), supplementing radar picket destroyers. Although these were relegated to secondary roles after the war, in the mid-1950s, 36 more DEs were converted to DERs, serving as such until 1960–1965. Their mission was to extend the Distant Early Warning Line on both coasts, in conjunction with 16 Guardian-class radar picket ships, which were converted Liberty ships.
During World War II, some 95 destroyer escorts were converted by the US to high-speed transports (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 (LCVPs) could be launched.

## Origins

The Lend-Lease Act was passed into law in the United States in March 1941, enabling the United Kingdom to procure merchant ships, warships, munitions, and other materiel from the US, 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 antisubmarine 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 escorts on 25 January 1943 and taken over by the United States Navy.
When the United States entered the war, and found they also required an antisubmarine 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.

## Alternatives

Destroyer escorts were designed and built to naval construction standards, and as such could only be built at yards experienced with naval standards. The United States Maritime Commission created its S2-S2-AQ1 design – which was based on the British-designed River class – for much the same role but using civilian construction standards. These ships would be classed by the Navy as the Tacoma class frigates (PF). These frigates had a greater range than the superficially similar destroyer escorts, but the US Navy viewed them as decidedly inferior in all other respects. The Tacoma class had a much larger turning circle than destroyer escorts, lacked sufficient ventilation for warm-weather operations (a reflection of their original British design and its emphasis on operations in the colder North Atlantic Ocean), were criticized as far too hot below decks, and, because of the mercantile style of their hulls, had far less resistance to underwater explosions than ships built to naval standards like the destroyer escorts.

## Post–World War II U.S. ship reclassification

After World War II, new-build United States Navy destroyer escorts were referred to as ocean escorts, 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. To remedy this problem, the 1975 ship reclassification declared ocean escorts (and by extension, destroyer escorts) as frigates (FF). This brought the USN's nomenclature more in line with NATO, and made comparing ship types with the Soviet Union easier. As of 2006, no plans existed for future frigates for the US Navy. USS Zumwalt and the littoral combat ship (LCS) were the main ship types planned in this area. However, by 2017 the Navy had reversed course, and put out a Request For Proposals (RFP) for a new frigate class, temporarily designated FFG(X). 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 is the Ticonderoga-class air-defense ship class, which is classified as cruiser, though it uses the same hull as the Spruance-class destroyers.

## Vietnam War

During the Vietnam War, the Republic of Vietnam Navy received two Edsall-class destroyer escorts from the United States.

## US Navy destroyer escort classes

| Class name | Propulsion | Guns | Torpedoes | Lead ship | Commissioned | Ships built |
| Evarts (GMT) | diesel - electric | 3 × 3in/50 | 0 | USS Evarts (DE-5) | 15 April 1943 | 97 |
| Buckley (TE) | turbo - electric | 3 × 3in/50 | 3 × 21in | USS Buckley (DE-51) | 30 April 1943 | 148 |
| Cannon (DET) | diesel - electric | 3 × 3in/50 | 3 × 21in | USS Cannon (DE-99) | 26 September 1943 | 72 |
| Edsall (FMR) | geared diesel | 3 × 3in/50 | 3 × 21in | USS Edsall (DE-129) | 10 April 1943 | 85 |
| Rudderow (TEV) | turbo - electric | 2 × 5in/38 | 3 × 21in | USS Rudderow (DE-224) | 15 May 1944 | 22 |
| John C. Butler (WGT) | geared turbine | 2 × 5in/38 | 3 × 21in | USS John C. Butler (DE-339) | 31 March 1944 | 83 |
| Dealey | geared turbine | 4 × 3in/50 | 4 × 21in | USS Dealey (DE-1006) | 3 June 1954 | 13 |
| Claud Jones | diesel | 2 × 3in/50 | 6 × 13in | USS Claud Jones (DE-1033) | 10 February 1959 | 4 |
| Bronstein | geared turbine | 2 × 3in/50 Mk33, ASROC | 6 × 13in | USS Bronstein (DE-1037) | 15 June 1963 | 2 |
| Garcia | geared turbine | 2 × 5in/38 | | USS Garcia (DE-1040) | 21 December 1964 | 10 |
| Brooke | geared turbine | 1 × 5in/38 | | USS Brooke (DEG-1) | 12 March 1966 | 6 |
| Knox | geared turbine | 1 x 5in/54 | | USS Knox (DE-1052) | 12 April 1969 | 46 |
* ↑ the first ship commissioned of the class was HMS Bayntun on 20 January 1943

## World War II shipbuilding programs

total ships in the table: 507DEs + 56APDs
37 Buckleys listed here as Buckleys were converted to APDs after having been commissioned as destroyer escorts. All APDs listed in the table were completed as conversions. Captains were converted before commissioning as DEs.
| Builder | State | Evarts + Captain | Buckley + Captain (+Charles Lawrence APDs) | Cannon | Edsall | Rudderow (+Crosley APDs) | Butler | total |
| (laid down from) | | Feb 1942 | Jul 1942 | Oct 1942 | Jun 1942 | Jul 1943 | Aug 1943 | |
| (launched until) | | Feb 1944 | May 1944 | Aug 1944 | Dec 1943 | Apr 1944 | Aug 1944 | |
| (commissioned from) | | Apr 1943 | Apr 1943 | May 1943 | Apr 1943 | Dec 1943 | Dec 1943 |
| (commissioned until) | | Aug 1944 | Jul 1944 | Dec 1944 | Feb 1944 | Sep 1944 | Dec 1945 | |
| Consolidated Steel | TX | | 12 (+6) | | 47 | (+3) | 34 | 93 |
| Bethlehem (Fore River and Hingham) | MA | | 27 + 46 | | | 14 (+23) | | 87 |
| Bethlehem, San Francisco | CA | | 12 | | | | | 12 |
| Boston Navy Yard | MA | 21 + 31 | | | | | 10 | 62 |
| Brown Shipbuilding | TX | | | | 38 | | 23 | 61 |
| Federal Shipbuilding and Drydock Company | NJ | | | 36 | | | 16 | 52 |
| Mare Island Navy Yard | CA | 31 | | | | | | 31 |
| Philadelphia Navy Yard | PA | 5 + 1 | 10 | | | 2 (+4) | | 18 |
| Dravo Corporation | DE, PA | | 3 (PA) | 15 (DE) | | | | 18 |
| Charleston Navy Yard | SC | | 15 | | | 2 (+9) | | 17 |
| Defoe Shipbuilding Company | MI | | 13 | | | 4 (+11) | | 17 |
| Western Pipe and Steel Company | CA | | | 12 | | | | 12 |
| Norfolk Navy Yard | VA | | 10 | | | | | 10 |
| Tampa Shipbuilding Company | FL | | | 9 | | | | 9 |
| Puget Sound Navy Yard | WA | 8 | | | | | | 8 |
| company | contract | issued | amount | delivery | description |
| various navy yards | | 11/41 | | | DE-1 ... DE-50 |
| Consolidated Steel | OBS378 | 1/42 | $110,426,000 | 9/43 | destroyer escorts DE 129-152 |
| Brown Shipbuilding | OBS403 | 1/42 | $63,558,000 | 10/43 | destroyer escorts DE 238-255 |
| Federal Shipbuilding and Drydock Company | OBS401 | 1/42 | $85,440,000 | 2/44 | destroyer escorts DE 162-197 |
| Dravo Corporation, Wilmington | OBS377 | 1/42 | $52,903,000 | 4/44 | destroyer escorts DE 99-128 |
| Bethlehem, Hingham | OBS376 | 2/42 | $118,800,000 | 12/43 | destroyer escorts DE 51-98 |
| Brown Shipbuilding | OBS335 | 8/42 | $151,833,000 | 7/44 | destroyer escorts DE 382-437 |
| Consolidated Steel | OBS334 | 8/42 | $197,505,000 | 11/44 | destroyer escorts DE 316-381 |
| Bethlehem, San Francisco | OBS331 | 8/42 | $28,427,000 | 7/44 | destroyer vessels DE 633-664 |
| Federal Shipbuilding and Drydock Company | OBS333 | 8/42 | $44,560,000 | 3/45 | destroyer escorts DE 438-515 |
| Bethlehem, Hingham | OBS332 | 8/42 | $155,364,000 | 8/45 | destroyer escorts DE 563-632 |
| Defoe Shipbuilding Company | OBS795 | 10/42 | $54,366,000 | 9/44 | destroyer escorts DE 693-738 |
| Bethlehem, Fore River | OBS840 | 10/42 | $35,365,000 | 11/44 | destroyer escorts DE 675-692 |
| Consolidated Steel | OBS844 | 11/42 | $42,372,000 | 3/44 | destroyer escorts DE 789-904 |
| Dravo Corporation, Pittsburgh | OBS841 | 11/42 | $11,845,000 | 4/44 | destroyer escorts DE 665-674 |
| Western Pipe and Steel Company | OBS842 | 11/42 | $44,132,000 | 9/44 | destroyer escorts DE 739-762 |
| Tampa Shipbuilding Company | OBS843 | 11/42 | $31,779,000 | 12/44 | destroyer escorts DE 763-788 |
Data from "Ship's Data U.S. Naval Vessels"
| Class | Company | Contract | Value | Hulls |
| WGT | C.Steel | 8/42 | $2,043,000 | 339-368 |
| WGT | federal | 8/42 | $2,785,000 | 438-450, 508-510 |
| WGT | Brown | 8/42 | $2,517,000 | 402-424 |
| FMR | C.Steel | 1/42 | $1,988,000 | 129-149 |
| FMR | C.Steel | 8/42 | $1,539,000 | 316-336 |
| FMR | Brown | 1/42 | $2,921,000 | 250-252 |
| FMR | Brown | 8/42 | $2,183,000 | 389-400 |
hull numbers for WGT and FMR are still incomplete, price of $2,157 for Brown/WGT DE-423 is assumed to be a typo
other classes missing (work in progress)
From the same document, List of Naval Vessels, pp. 11:
| Type | Hulls | Cancelled Hulls |
| GMT | 5-50 | |
| TE | 51-98 | |
| DET | 99-113 | 114-128 |
| FMR | 129-152 | |
| TE | 153-161 | |
| DET | 162-197 | |
| TE | 198-223 | |
| TEV | 224-237 | |
| FMR | 238-255 | |
| GMT | 256-283 | 284-300 |
| GMT | 301-307 | 308-315 |
| FMR | 316-338 | |
| WGT | 339-372 | 373-381 |
| FMR | 382-401 | |
| WGT | 402-424 | 425-437 |
| WGT | 438-450 | 451-507 |
| WGT | 508-510 | 511-515 |
| GMT | 516-530 | |
| WGT | 531-542 | 543-562 |
| TE | 563-578 | |
| TEV | 579-606 | 607-632 |
| TE | 633-636 | |
| GMT | 637-644 | |
| TEV | | 645-664 |
| TE | 665-673 | |
| TEV | 674 | |
| TE | 675-683 | |
| TEV | 684-692 | |
| TE | 693-705 | |
| TEV | 706-722 | 723-738 |
| DET | 739-750 | 751-762 |
| DET | 763-771 | 772-788 |
| TE | 789-800 | 801-1005 |

## Captain-class frigates of the Royal Navy

The Captain class was a designation given to 78 frigates of the Royal Navy, constructed in the United States, launched in 1942–1943 and delivered to the United Kingdom under the provisions of the Lend-Lease agreement (under which the United States supplied the United Kingdom and other Allied nations with materiel between 1941 and 1945), they were drawn from two subclasses of the destroyer escort (originally British destroyer escort) classification: 32 from the Evarts subclass and 46 from the Buckley subclass. Upon reaching the UK, the ships were substantially modified by the Royal Navy, including removal of torpedo tubes, making them distinct from the US Navy destroyer escort ships.
Captain-class frigates acted in the roles of convoy escorts, antisubmarine 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 postwar period, all of the surviving Captain-class frigates except one (HMS Hotham) were returned to the US Navy before the end of 1947 to reduce the amount payable under the provisions of the Lend-Lease agreement; the last such 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 (MDAP).
* FFL Algérien (F-1), ex-Cronin (DE-107)
* FFL Sénégalais (F-2), ex-Corbestier (DE-106)
* FFL Somali (F-3), ex-Somali (DE-111)
* FFL Hova (F-4), ex-Hova (DE-110)
* FFL Marocain (F-5), ex-Marocain (DE-109)
* FFL Tunisien (F-6), ex-Crosley (DE-108)

## Mutual Defense Assistance Program – Post WWII

Under the MDAP the destroyer escorts leased to the Free French were permanently transferred to the French Navy. In addition, the following navies also acquired DEs:

### Republic of China Navy (Taiwan)

    DE-47, DE-6

### French Navy

    DE-1007, DE-1008, DE-1009, DE-1010, DE-1011, DE-1012, DE-1013, DE-1016, DE-1017, DE-1018, DE1019

### Hellenic Navy

    DE-173, DE-766, DE-768, DE-193

### Italian Navy

    DE-1020, DE-1031

### Japanese Maritime Self-Defense Force

    DE-168, DE-169

### Philippine Navy

    DE-168, DE-169, DE-170, DE-770, DE-771, DE-251, DE-637

### Portuguese Navy

    DE-509, DE-1032, DE-1039, DE-1042, DE-1046

### Republic of Korea Navy

    DE-770, DE-771

### Royal Navy

DE-574

### Royal Netherlands Navy

    USS Burrows (DE-105), USS Rinehart (DE-196), USS Gustafson (DE-182), USS O'Neill (DE-188), USS Eisner (DE-192), USS Stern (DE-187)

### Royal Thai Navy

    DE-746

### National Navy of Uruguay

    DE-166, DE-189,

## Comparison with contemporary frigates

The table below compares destroyer escorts and frigates designed for similar missions.
| Name | Date | Nation | Displacement | Speed | Number built | Notes |
| River-class frigate | 1942 | UK | 1,370 tons | 20 knots | 151 | |
| Type A Kai kaibōkan | 1943 | Japan | 870 tons | 19 knots | 18 | |
| FMR class | 1943 | US | 1,200 tons | 21 knots | 85 | |
| Evarts-class | 1943 | US | 1,140 tons | 21 knots | 72 | |
| Buckley-class | 1943 | US | 1,400 tons | 23 knots | 102 | |
| Cannon-class | 1943 | US | 1,240 tons | 21 knots | 72 | |
| Tacoma-class frigate | 1943 | US | 1,430 tons | 20 knots | 96 | |
| Type B kaibōkan | 1943 | Japan | 940 tons | 19 knots | 37 | |
| Loch-class frigate | 1944 | UK | 1,435 tons | 20 knots | 30 | anti-submarine |
| WGT class | 1944 | US | 1,350 tons | 24 knots | 87 | |
| TEV class | 1944 | US | 1,450 tons | 24 knots | 22 | |
| Bay-class frigate | 1945 | UK | 1,580 tons | 20 knots | 26 | anti-aircraft, built on Loch class hulls |
| Type 15 frigate | 1952 | UK | 2,300 tons | 31 knots | 23 | Rebuilds of War Emergency Programme destroyers into anti-submarine frigates |
| Dealey class | 1954 | US | 1,450 tons | 25 knots | 13 | |
| Type E50 frigate | 1955 | France | 1,290 tons | 28 knots | 4 | fast |
| Type 14 frigate | 1955 | UK | 1,180 tons | 24 knots | 15 | Also known as Blackwood-class. "second-rate" anti-submarine warfare frigates. Cheaper to produce than Type 12. |
| St. Laurent class | 1955 | Canada | 2,263 tons | 28 knots | 7 | anti-submarine |
| Type B | 1956 | Japan | 1,070 tons | 25 knots | 2 | diesel |
| Type 12 frigate | 1956 | UK | 2,150 tons | 31 knots | 8 | Also known as Whitby class. Anti-submarine frigates for combating fast submarines |
| Type E52 frigate | 1956 | France | 1,295 tons | 28 knots | 14 | fast |
| Almirante Clemente-class light destroyer | 1956 | Venezuela | 1,300 tons | 32 knots | 6 | fast |
| Type 61 frigate | 1957 | UK | 2,170 tons | 24 knots | 4 | Salisbury class. aircraft direction |
| Centauro-class frigate | 1957 | Italy | 1,807 tons | 26 knots | 4 | |
| Type 41 frigate | 1957 | UK | 2,300 tons | 24 knots | 7 | Leopard class. anti-aircraft escort for convoys |
| Azopardo-class frigate | 1957 | Argentina | 1,160 tons | 20 knots | 2 | |
| Restigouche class | 1958 | Canada | 2,366 tons | 28 knots | 7 | anti-submarine |
| Claud Jones class | 1959 | US | 1,450 tons | 22 knots | 4 | |
| Type 12M frigate | 1960 | UK | 2,380 tons | 30 knots | 14 | Rothesay class. ."Modified" Type 12. Anti-submarine |
| Köln-class frigate | 1961 | Germany | 2,100 tons | 30 knots | 6 | fast |
| River-class destroyer escort | 1961 | Australia | 2,100 tons | 30 knots | 6 | Originally designated as anti-submarine frigates, later re-designated as destroyer escorts. Four built to British Type 12M design, two built to Type 12I design |
| Isuzu-class destroyer escort | 1961 | Japan | 1,490 tons | 25 knots | 4 | |
| Type 81 frigate | 1961 | UK | 2,300 tons | 28 knots | 7 | Tribal-class. Originally multi-role ("general purpose") sloops for Middle East. Reclassified as "second class" frigates. |
| Bergamini-class frigate | 1961 | Italy | 1,410 tons | 26 knots | 4 | |
| Commandant Rivière-class frigate | 1962 | France | 1,750 tons | 25 knots | 13 | dual purpose |
| Mackenzie class | 1962 | Canada | 2,366 tons | 28 knots | 4 | anti-submarine |
| Hvidbjørnen-class frigate | 1962 | Denmark | 1,345 tons | 18 knots | 4 | fishery protection |
| Type 12I frigate | 1963 | UK | 2,450 tons | 30 knots | 28 | Leander class. "Improved" Type 12. General purpose. Also built as Nilgiri-class frigate (India, 6), Condell-class (Chile, 2), River-class (Australia,2) |
| Bronstein class | 1963 | US | 2,360 tons | 26 knots | 2 | |
| Garcia class | 1964 | US | 2,620 tons | 27 knots | 10 | |
| Oslo-class frigate | 1966 | Norway | 1,450 tons | 25 knots | 5 | |
| Brooke class | 1966 | US | 2,640 tons | 27 knots | 6 | guided missile |
| Peder Skram-class frigate | 1966 | Denmark | 2,030 tons | 28 knots | 2 | fast |
| Van Speijk-class frigate | 1967 | Netherlands | 2,200 tons | 28 knots | 6 | Dutch version of the British Leander |
| Alpino-class frigate | 1968 | Italy | 2,000 tons | 28 knots | 2 | |
| Alvand-class frigate | 1968 | Iran | 1,110 tons | 40 knots | 4 | |
| Knox class | 1969 | US | 3,011 tons | 27 knots | 46 | |
| Chikugo-class destroyer escort | 1971 | Japan | 1,470 tons | 25 knots | 11 | |

## Surviving destroyer escorts

Four destroyer escorts are preserved as museum ships, while others remain in active service.
* The Edsall-class destroyer escort USS Stewart (DE-238) is preserved in Galveston, Texas.
* The Cannon-class destroyer escort USS Slater (DE-766) is preserved in Albany, New York.
* The Cannon-class destroyer escort BNS Bauru (BE-4), formerly USS McAnn (DE-179) is preserved in Rio de Janeiro, Brazil.
* The modified Rudderow-class destroyer escort, ARC Cordoba (DT-15), formerly USS Ruchamkin (APD-89) is preserved in Tocancipa, Colombia.
* The Cannon-class destroyer escort HTMS Pin Klao (DE-1), formerly USS Hemminger (DE-746), is active in the Royal Thai Navy as a training ship. She is the last operational World War II destroyer escort in any navy.
* The Japanese Maritime Self-Defense Force operates six Abukuma-class destroyer escorts.