Destroyer Escorts in World War II
Relatively little consideration was given to anti-submarine warfare or convoy escort in the years between the world wars for a number of rea-sons. Some military experts believed that the next war would be fought entirely in the air; others felt that improved acoustic detection devices would make submarines easy to locate and destroy. When war erupted in Europe in September of 1939 the British Navy was ill-equipped for combating German submarines. Fortunately for the British, the German Navy had only 57 operational U-boats and would require more than a year to build up a viable force of submarines. (The Germans also would employ large surface warships, battleships and cruisers, and heavily armed merchant ships disguised as Allied freighters in the merchant-raider role.)
The United States was able to profit from the British Anti-Submarine Warfare (ASW) from 1939 to 1941 and had time before entering the conflict to begin massive ship construction programs. During the years 1942 to 1945 the nation's shipyards built some 1,300 small ASW ships (between 100 and 200 feet in length) arid more than 600 large ASW ships (approximately 300 feet long), and converted hun-dreds of yachts and trawlers to fight submarines. These yards also built several hundred destroyers and more than 100 escort or "jeep" aircraft carriers that were highly effective in the ASW role.
The most important ASW ships probably were the so-called Destroyer Escorts (designated DE). These ships essentially were small destroyers fitted with about half the power plant of a destroyer (giv-ing the DE a speed of about 20 knots compared with almost 35 knots for a war-built destroyer). The DE carried fewer guns and torpedo tubes than a destroy-er but had the same general anti-submarine capabili-ties as the larger ship.
The DE was fitted with acoustic detection equipment (referred to as sonar for SOund Naviga-tion And Ranging) and ASW weapons. Initially the DE carried only depth charges, rolled off the stern and fired from side launchers. The depth charges were made more streamlined, being given almost a bomb shape so they would sink to their exploding depth more rapidly.
Still, depth charges had two principal disadvantages: First, they required the attacking ship to overrun the submarine, meaning that for a few moments the ship's own propeller and movement sounds would blank out the U-boat noises; second, the depth charges, pre-set to explode at the sub-marine's estimated depth, would always explode and this further masked any submarine sounds. Under these circumstances there were several min-utes when the submarine could not be heard and unless it sustained damage from the exploding pat-tern of depth charges could use the opportunity to evade pursuers.
To overcome these limitations the ahead-throwing hedgehog was developed. This weapon fired 24 relatively small, rocket-like projectiles into the water some 250 yards ahead of the escort ship. The projectiles entered the water in a large, circular pattern and plummeted through the depths, explod-ing only upon contact with a submarine hull. Al-though the 31-pound explosive charge was smaller than a depth charge, it could still inflict significant damage on a submarine. The weapon was dubbed "hedgehog" because the launcher spigots which held the projectiles were somewhat akin to the protruding quills of a porcupine or hedgehog.
When armed with the hedgehog, the destroyer or destroyer escort could keep sonar contact with the submarine throughout the attack, without the ship's detection equipment being impaired by the ship's own noises or exploding depth charges. Also, there was no need to estimate the submarine's depth because the projectiles exploded upon contact.
Another technological development that became a key in ASW during World War II was radar (for RAdio Detection And Ranging). Radar trans-mits radio waves in narrow beams to detect objects in darkness or fog and at greater distances in clear weather than the human eye can see. Escort ships were provided with radar to enable them to detect U-boats on the surface at night and in fog or their periscopes when submerged.
Fitted with depth charges, the ahead-firing hedgehog, and radar as well as sonar, the destroyer escort was a most-important member of allied ASW forces in World War II. Other components of allied ASW forces included land-based aircraft and blimps, escort or "jeep" aircraft carriers and their planes, destroyers, and the many types of smaller ASW ships and craft; Allied submarines also had a limited role in anti-submarine operations.
The first 50 destroyer escorts were ordered in November 1941 -- just prior to U.S. entry into World War II -- with Lend Lease funds. This meant that the Congress had appropriated money for building the ships for transfer to Britain. However, by the time the first ships were launched in June of 1942, the United States was in the war and only six of those original 50 DEs went to the Royal Navy, the others commissioned for U.S. service.
Contracts were quickly placed for hundreds of additional destroyer escorts as the battle against German U-boats in the Atlantic was given top priority for the Allies. Without safe Allied use of the Atlantic shipping lanes Britain could not survive, and there could be no Allied troop landings on Axis-held portions of Africa or Europe.
Seventeen U.S. shipyards participated in the DE construction program, and they built more than 500 DE-type ships before the end of the war. These ships saw action in virtually every area of the con-flict with almost one hundred being modified to serve as high-speed transports, each carrying up to 160 commandos, underwater swimmers (frogmen), or amphibious landing control personnel. Other DEs were transferred to the British, French, and Brazilian navies to help in the war.
The hundreds of escort ships that fought under the U.S. flag attacked German, Italian, and Japanese submarines. Sometimes the DEs were part of mer-chant convoy escorts; at other times they protected amphibious landing forces; and sometimes they teamed up with escort aircraft carriers to form "hunter-killer" teams that sought out enemy sub-marines. Perhaps the most remarkable DE was the ENGLAND, under Commander W. B. Pendleton, which sank five Japanese submarines and provided a major assist in sinking another within a hectic 12-day period in 1944. This is a one-ship record for ASW successes rivaled only by the six German U-boat sinkage attributed to ships successively commanded by Captain Donald Macintyre, Royal Navy. In all, the U.S. escort ships were credited with the sinking of 48 German, two Italian, and 68 Japanese submarines.
Although intended primarily as anti-submarine ships, the DEs were pitted against intense air attacks, especially in the Pacific War-including Japanese suicide planes or kamikazes, and against the largest battleship ever built.
The only DE-versus-battleship came in October of 1944 off the eastern coast of the Philippines when several groups of escort aircraft carriers were providing air support for U.S. landings on the island of Leyte. The "jeep" carriers were being screened by destroyers and destroyer escorts. Suddenly and without warning, the characteristic pagoda masts of Japanese battleships and cruisers appeared over the horizon. The Japanese force, in-cluding the 67,000-ton battleship YAMATO, the largest warship afloat, had evaded air patrols and was bearing down to attack the U.S. transports beyond the escort carriers. The several destroyers and escort ships turned toward the Japanese to protect the fleeing carriers (whose planes were armed for attack-ing enemy troops ashore, and did not have armor-piercing bombs or torpedoes needed to sink warships). In the furious melee that followed the Japanese battleships and cruisers were turned back by the ferocity of the U.S. counterattacks. Two of the U.S. destroyers and one DE, half the U.S. screening force, were sunk as was one of the escort carriers, and several U.S. ships were damaged.
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