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Underwater Demolition Teams


UNDERWATER DEMOLITION TEAMS (UDTs) are special units of the United States Navy. During World War II, Germany and Japan devised extensive underwater defenses in anticipation of Allied amphibious landings. The U.S. Marines assault at Tarawa Island in the western Pacific in November 1943 demonstrated the need to detect and destroy underwater obstructions and mines close to shore, where minesweepers could not go. The U.S. Navy organized intensively trained men into teams of expert swimming scouts whose duties were the reconnaissance of the seaward approaches to landing beaches; the location, improvement, and marking of usable channels for landing craft; and the demolition of natural and artificial obstacles. Often swimming two miles in shallow waters over coral reefs, under fire by the enemy in broad daylight, these men, nicknamed "frogmen," were unarmed except for a sheath knife. Working underwater, they scouted shores, demolished reef barriers, and neutralized enemy mines. UDTs were "first in" at Kwajalein, Saipan, Tinian, Guam, Peleliu, Anguar, Leyte, Lingayen, Luzon, Borneo, Iwo Jima, and Okinawa in the Pacific. In Europe, UDTs combined with U.S. Army beach clearance personnel at Normandy and in southern France in 1944 and suffered heavy casualties during the Normandy landings. During the Korean War, UDTs prepared the way for the amphibious Inchon landing and cooperated with special U.S. Marine Corps raider units striking far inland to blow up bridges, tunnels, dams, power plants, and highways. In the Vietnam War special volunteer units recruited from UDTs called SEALs (Sea-Air-Land approaches) made intelligence forays and commando raids into Vietcong-held territory in South Vietnam.


Fane, Francis D., and Don Moore. The Naked Warriors. New York: Appleton-Century-Crofts, 1956.

Fawcett, Bill, ed. Hunters and Shooters: An Oral History of the U.S. Navy Seals in Vietnam. New York: Morrow, 1995.

Hutchins, Joel. Swimmers among the Trees: SEAL Operations in the Vietnam War. Novato, Calif.: Presidio, 1996.

Welham, Michael. Combat Frogmen: Military Diving from the Nineteenth Century to the Present Day. Welling borough, U.K.: Stephens, 1989.

James J.Stokesberry/e. m.

See alsoKorean War ; Navy, United States ; Vietnam War ; World War II .

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