The Underwater Demolition Team (UDT), or frogmen, were amphibious units created by the United States Navy during World War II with specialized missions. They were predecessors of the Navy's current SEAL teams. Their primary WWII function began with reconnaissance and underwater demolition of natural or man-made obstacles obstructing amphibious landings. Postwar they transitioned to scuba gear changing their capabilities. With that they came to be considered more elite and tactical during the Korean and Vietnam Wars. UDTs were pioneers in underwater demolition, closed-circuit diving, combat swimming, riverine warfare and midget submarine (dry and wet submersible) operations. They later were tasked with ensuring recovery of space capsules and astronauts after splash down in the Mercury, Gemini and Apollo space flight programs. Commando training was added making them the forerunner to the United States Navy SEAL program that exists today. By 1983, the UDTs were re-designated as SEAL Teams or Swimmer Delivery Vehicle Teams (SDVTs); however, some UDTs, had already been re-designated into UCTs and special boat units prior. SDVTs have since been re-designated SEAL Delivery Vehicle Teams.
Early history
The United States Navy studied the problems encountered by the disastrous Allied amphibious landings during the Gallipoli Campaign of World War I. This contributed to the development and experimentation of new landing techniques in the mid-1930s. In August 1941, landing trials were performed and one hazardous operation led to Army Second Lieutenant Lloyd E. Peddicord being assigned the task of analyzing the need for a human intelligence (HUMINT) capability. When the U.S. entered World War II, the Navy realized that in order to strike at the Axis powers the U.S. forces would need to perform a large number of amphibious attacks. The Navy decided that men would have to go in to reconnoiter the landing beaches, locate obstacles and defenses, as well as guide the landing forces ashore. In August 1942, Peddicord set up a recon school for his new unit, Navy Scouts and Raiders, at the amphibious training base at Little Creek, Virginia. In 1942, the Army and Navy jointly established the Amphibious Scout and Raider School at Fort Pierce, Florida. Here Lieutenant Commander Phil H. Bucklew, the "Father of Naval Special Warfare", helped organize and train what became the Navy's 'first group' to specialize in amphibious raids and tactics. The need for intelligence gathering prior to landings became paramount following the amphibious assault at the Battle of Tarawa in November 1943. Although Navy and Marine Corps planners had identified coral as an issue, they incorrectly assumed landing craft would be able to crawl over the coral. Marines were forced to exit their craft in chest deep water a thousand yards from shore, with many men drowning due to the irregularities of the reefs and Japanese gunners inflicting heavy U.S. casualties. After that experience, Rear Admiral Kelley Turner, Commander of the V Amphibious Corps (VAC), directed Seabee Lt. Crist (CEC) to come up with a means to deal with the coral and the men to do it. Lt. Crist staged 30 officers and 150 enlisted men from the 7th Naval Construction Regiment at Waipio Amphibious Operating Base on Oahu to form the nucleus of a reconnaissance and demolition training program. It is here that the UDTs of the Pacific were born. Later in war, the Army Engineers passed down demolition jobs to the U.S. Navy. It then became the Navy's responsibility to clear any obstacles and defenses in the near shore area. A memorial to the founding of the UDT has been built at Bellows Air Force Station near the original Amphibious Training Base (ATB) in Oahu.
Naval Combat Demolition Units
In early May 1943, a two-phase "Naval Demolition Project" was ordered by the chief of naval operations (CNO) "to meet a present and urgent requirement". The first phase began at Amphibious Training Base (ATB) Solomons, Maryland, with the establishment of Operational Naval Demolition Unit No. 1. Six officers and eighteen enlisted men reported from the Seabees dynamiting and demolition school at Camp Peary for a four-week course. Those Seabees were immediately sent to participate in the invasion of Sicily, where they were divided in three groups that landed on the beaches near Licata, Gela and Scoglitti. Also in May, the Navy created Naval Combat Demolition Units (NCDUs) tasked with eliminating beach obstructions in advance of amphibious assaults, going ashore in an LCRS inflatable boat. Each NCDU consisted of five enlisted men led by a single, junior (CEC) officer. In early May, Chief of Naval Operations Admiral Ernest J. King picked Lieutenant Commander Draper L. Kauffman to lead the training. The first six classes graduated from "Area E" at the Seabee's Camp Peary between May and mid-July. Training was moved to Fort Pierce, Florida, where the first class began mid-July 1943. Despite the move and having the Scouts Raiders base close by, Camp Peary was Kauffman's primary source of recruits. "He would go up to Camp Peary's Dynamite School and assemble the Seabees in the auditorium saying: I need volunteers for hazardous, prolonged and distant duty." Kauffman's other volunteers came from the U.S. Marines and U.S. Army combat engineers. Training commenced with one grueling week designed to "separate the men from the boys". Some said that "the men had sense enough to quit, leaving Kauffman with the boys." It was and is still considered the first "Hell Week".
Normandy In early November 1943, NCDU-11 was assigned as the advance NCDU party for Operation Overlord. They would be joined in England by 33 more NCDUs. They trained with the 146th, 277th, and 299th Combat Engineers to prepare for the landing. Each Unit had five combat engineers attached to it. The first 10 NCDUs divided into three groups. The senior officer, by rank, was the commanding officer of Group III, Lieutenant Smith (CEC). He assumed command in an unofficial capacity. His Group III worked on experimental demolitions and developed the Hagensen Pack, an innovation that used 2.5-pound (1.1 kg) of tetryl placed into rubber tubes that could be twisted around obstacles. As more teams arrived, a NCDU Command was created for NCDUs: 11, 22–30, 41–46, 127–8, and 130–42.
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