In World War II as in World War I, the United States and its allies faced a threat from German submarines, whose numbers and effectiveness threatened to close Atlantic sea lanes, jeopardizing the war effort in Europe. At first, forces with anti-submarine capabilities—destroyers, coast guard cutters, other smaller ships and land-based aircraft—were not available in sufficient numbers or organized to counter this menace. That the Battle of the Atlantic was decisively won was due in no small measure to the arrival of specialized “destroyer escorts” (DEs) and the “hunter-killer” task forces they formed with small aircraft carriers which, in the last two years of the war, nearly eliminated the U-boat threat.

The evolution of destroyer escort design dated back to 1939, when basic characteristics were established for ships that could be built rapidly and in large numbers without interfering with production of machinery and armament for other types. A ~300-foot hull needed only 10–20 per cent of the horsepower of a contemporary destroyer to achieve 21–24 knots, sufficient for the task. Steam or diesel power could be used; 5-inch guns were preferred but 3-inch would do. Close-in anti-aircraft defenses evolved as in destroyers from the ineffective 1.1-inch cannon to the standard 40mm and 20mm weapons. Torpedoes were initially carried in some classes in case of a surface threat, and of course there were depth charges and hedgehogs plus sonar and radar that were essential to their mission.

Over a 19-month period beginning in November 1941, the US Navy placed orders for 1,005 destroyer escorts in six classes. At first, the need for new shipyard capacity and construction priorities such as larger surface ships and landing craft slowed production—keels were laid for the first destroyer escorts only in February 1942 and the first of them commissioned only in January 1943.

Even as DEs began began to join the fleet, however, Allied code-breakers, ships and aircraft and the convoy system were stemming the tide in the Battle of the Atlantic. In May 1943, while German and Italian U-boats sank 45 Allied merchant ships they lost an equal number of their own, reducing their average number in daily operation by more than 25 per cent thereafter. The US Navy soon realized that many more destroyer escorts had been ordered than would be needed and began canceling orders in September.

Eventually, 563 DEs and conversions were delivered, all but six by the end of the war (the last two were delayed until 1955). Seventy-eight ships went directly to Great Britain; six went to France. Of the 479 DEs first commissioned in the US Navy, eight were transferred to Brazil later in World War II, 38 were converted as fast transports (APD) and 56 were completed as APDs, adding their numbers to the four-stack “Green Dragons.” Most of the US Navy ships were deployed in the Atlantic, but some also went to the Pacific, where they were equally effective in anti-submarine roles.

After World War II, the US Navy retained many of its DEs and APDs until approximately 1960 and some into the 1970s. Meanwhile, new classes of specialized anti-submarine ships were built beginning with the Dealey class ocean escorts and culminating in the present Oliver Hazard Perry-class helicopter-carrying guided missile frigates.

Today, one World War II destroyer escort is afloat and on display—the Cannon-class Slater (DE 766), beautifully restored to end-of-war appearance at Albany, New York. A second, the Edsall-class Stewart (DE 238) is on static display at Galveston, Texas. Activities are conducted by members of the Destroyer Escort Sailors Association (DESA), which also maintains an extensive web site with ships’ histories and photos. (continued)

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Sources: Friedman, Morison, Vol. X, Destroyer History database.