Destroyer Escorts in World War I
Since man first went to sea in ships to trade and reap the harvests of the sea, other men have used ships to interfere with those vessels engaged in law-ful activities. Those men who sailed the latter ships often were pirates, brigands who claimed allegiance to no state. As nations evolved and made war on one another, their warships attempted to disrupt the maritime trade and other commercial sea activities of their opponents.
Thus grew the need for ships to defend mer-chant ships against pirates in peacetime and enemy warships during war. These defending or "escort" ships were sometimes full-fledged warships. How-ever, because a nation's larger warships could often be better employed in fighting enemy fleets than in escorting merchant ships, smaller, lighter-armed ships usually were employed in the escort role.
Ships used for escort have varied throughout history, from older warships no longer suitable for first-line fighting, to merchant ships and even fishing craft that were equipped with guns to serve as "quasi--warships."
By the beginning of the 20th Century navies had a number of different types of escort ships: sloops, corvettes, frigates, gun-boats, and others. Their characteristics varied greatly, depending upon the navy and its requirements. In general, such ships were small and had limited capabilities.
World War I brought a new requirement for es-cort ships. Whereas the main threat to merchant shipping previously had been an enemy's surface warships, the submarine evolved as the primary com-merce raider in the 1914-1918 war.
Initially submarines-especially the German Un-terseeboat or U-boat-would approach enemy mer-chant ships on the surface, order them to stop, and search them to determine if they were carrying arms or other contraband material. If the merchant ship was found to be carrying war supplies, the subma-rine commander would order the ship abandoned and, after the merchant sailors were safe in lifeboats, the submarine would sink the ship.
Soon, Allied countermeasures were making such "civilized" submarine tactics very hazardous. Escort ships sometimes sailed with the merchantmen and the freighters, and transports were provided with guns. When the submarine surfaced it would be met with gunfire. Accordingly, submarine tactics changed. The enemy merchant ship would be tor-pedoed without warning. Also, during daylight hours the submarine would approach its victim and attack while submerged. This led to changes in escort tactics and equipment. At the beginning of the war the escort ship would visually search for and detect the submarine. Sailors would strain through binoculars to sight a surface U-boat or, if the submarine were submerged, the tell-tale periscope and its feather-like wake. Once the submarine was sighted the escort ship would attack with gunfire and then, if in a good position, attempt to ram the submarine.
Now, with the submarines attacking submerged, the escort ships were fitted with sound detection equipment. Initially these were hydrophones or listening instruments lowered into the water to hear the sounds' of a submarine's propellers. Once the submarine was detected, either visually or by sound, the escort ships would race for the sound "contact" with guns firing if part of the submarine or its periscope were visible. As the escort ship reached the contact, it would fire or release the new anti-submarine weapons that were being developed. The early weapons were a collection of unusual devices. Among them were "darts" with explosive heads that would be fired at the submarine and a "harpoon" carrying a line tied to an explosive charge that was intended to catch on the submarine's wooden over-deck. But the most practical and successful weapon became the depth charge.
Colloquially known as the "ash can," the depth charge resembled a trash can and was fitted with an explosive charge and a pressure-sensitive fuze that would detonate the explosive when the weapon reached a pre-set depth (as the pressure of water in-creases almost a half-pound per square inch with every foot of depth).
One problem with early depth charges was their scarcity. In early 1917 British destroyers were only allocated four of them, two fitted with 300 pounds of TNT and two containing 120 pounds of the ex-plosive. However, as factories produced more of the weapons, by year's end each destroyer had 20 to 30 upon going to sea.
It was estimated that a depth charge explosion could destroy a submarine at a distance of some 15 feet and damage one within some 30 feet. As with modern underwater weapons, damage is caused by the tremendous pressure wave generated by an ex-plosion. Even if the depth charge attack did not sink or damage the submarine, the explosions let the crew know that they were detected and that a destroyer or other escort ship was in the area. A depth charge attack could be a frightening psychological ordeal.
The effectiveness of depth charges, initially rolled off the stern of the escort ship when passing over the believed position of the submarine, was in-creased when the Y-gun was put in use in 1917. This was a two-barreled howitzer that could fire depth charges out 40 to 50 yards from each side of the ship. Coupled with the charges rolled off the stern, a Y-gun permitted a wider, pattern attack. Other "modern" weapons that joined the battle against submarines included mines, anchored to the floor to explode when a U-boat passed nearby, and aircraft, whose pilots could often see shallow-traveling submarines just under the surface and attack with bombs or depth charges.
When the United States entered World War I on April 6, 1917, the most urgent Allied requirement was for escort ships to convoy freighters bringing food, coal, and raw materials to Britain. At the time it was estimated that Britain had sufficient food supplies for less than a month. Immediately U.S. destroyers were dispatched across the Atlantic to join British escort forces. These ships soon were followed by newer destroyers as U.S. shipyards, having had three years for preparation, were able to tool up for mass production of destroyers. During the 18 months that the United States was at war the nation's shipyards completed 43 destroyers.
The scope of the submarine threat and the re-quirement for destroyers to support operations of the U.S. and British battle fleets led to the develop-ment of smaller anti-submarine craft and the conver-sion of hundreds of yachts and fishing craft for hunting U-boats. Among the smaller U.S. craft were the wooden SC-type patrol craft (called "splinter" boats) and the Eagle boats. U.S. shipyards built 448 of the 110-foot SC submarine chasers while the Ford Motor Company, America's great automobile producer, applied mass-production techniques to turn out 60 larger, 201-foot "Eagle" patrol escorts. As with the massive destroyer-building programs of the war, most of the smaller anti-submarine ships also were completed after the fighting stopped in November 1918.
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