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 RegimentSubmarine Blasting, 301 Naval Construction Battalion Cruisebook, Seabee Museum Archives website, Jan. 2020, p.60, Port Hueneme, CA. / 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.pp. 30–31 Dockery & Brutsman
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.p.34 Dockery, Kevin & Brutsman, Bud Navy SEALs A History of the Early Years Berkley Publishing 2001 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 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.Report on Naval Combat Demolition Units in Operation "Neptune" as part of Task Force 122, Submitted by: Lt.(jg) H. L. Blackwell, Jr. D-V(G), USNR, 5 July 1944
The Germans had constructed elaborate defenses on the French coast. These included steel posts driven into the beach and topped with explosive charges. Large 3-ton steel barricades, called Belgian Gates and hedgehogs, were placed throughout the tidal zone. Behind which was a network of reinforced coastal artillery, mortar and machine gun positions.
The NCDU teams (designated Demolitions Gap-Assault teams) would come in at low tide to clear the obstacles. Their mission was to open sixteen wide corridors for the landing at each of the U.S. landing zones (Omaha Beach and Utah Beach). Unfortunately, the plans were not executed as laid out. The preparatory air and naval bombardment was ineffective, leaving many German guns to fire on the assault. Also, tidal conditions caused difficulties for the NCDUs. Despite heavy German fire and casualties, the NCDUs charges opened gaps in the defenses.
As the infantry came ashore, some used obstacles for cover that had demolition charges on them. The greatest difficulty was on Omaha Beach. By nightfall, thirteen of the planned sixteen gaps were open. Of the 175 NCDU men that landed, 31 were killed, and 60 were wounded. The attack on Utah Beach was better, four dead and eleven wounded. Overall, NCDUs suffered a 53 percent casualty rate. NCDUs were also assigned to Operation Dragoon, the invasion of southern France, with a few units from Normandy participating there too.
With Europe invaded, Admiral Turner requisitioned all available NCDUs from Fort Pierce for integration into the UDTs for the Pacific. However, the first NCDUs, 1–10, had been staged at Turner City, Florida Island in the Solomon Islands during January 1944. A few were temporarily attached to UDTs. Later, NCDUs 1–10 were combined to form Underwater Demolition Team Able. This team was disbanded with NCDUs 2 and 3, plus three others assigned to MacArthur's 7th Amphibious force, and were the only NCDUs remaining at war's end. The other men from Team Able were assigned to numbered UDTs.
Underwater Demolition Teams During WWII
The first units designated as Underwater Demolition Teams were formed in the Pacific Theater. Rear Admiral Turner, the Navy's amphibious expert, ordered the formation of Underwater Demolition Teams in response to the assault debacle experienced at Tarawa. Turner recognized that amphibious operations required intelligence of underwater obstacles. The personnel in teams 1-15 were primarily Seabees that had started out in the NCDUs. UDT training was at the Waipio Amphibious Operating Base, under V Amphibious Corps operational and administrative control. Most of the instructors and trainees were graduates of the Fort Pierce NCDU or Scouts and Raiders schools, Seabees, Marines, and Army soldiers.
When Teams 1 and 2 were formed they were "provisional" and trained by a Marine Corps Amphibious Reconnaissance Battalion that had nothing to do with the Fort Pierce program. After a successful mission at Kwajalein, where 2 UDT men stripped down to swim trunks and effectively gathered the intelligence Admiral Turner desired, the UDT mission model evolved to daylight reconnaissance, wearing swim trunks, fins, and masks. The immediate success of the UDTs made them an indispensable part of all future amphibious landings.
A UDT was organized with approximately sixteen officers and eighty enlisted. One Marine and one Army officer were liaisons within each team.Commander, V Amphibious Corps to CinCPac, report, Underwater Demolition Teams, Recommendations Concerning-Based on Experience in Flintlock (Kwajalein), 2 June 1944, declassified from secret. They were deployed in every major amphibious landing after Tarawa with 34 teams eventually being commissioned. Teams 1–21 were the teams that had deployed operationally, with slightly over half of the officers and enlisted coming from the Seabees in those teams. The remaining teams were not deployed due to the war ending.
Tarawa and the formation of UDTs Prior to Tarawa, both Naval and Marine Corps planners had identified coral as an issue for amphibious operations. At Tarawa the neap tide created draft issues for the Higgins boats (LCVPs) clearing the reef. The Amtracs carrying the first wave crossed the reef successfully. The LCVPs carrying the second wave ran aground, disembarking their Marines several hundred yards to shore in full combat gear, under heavy fire. Many drowned or were killed before making the beach, forced to wade across treacherously uneven coral. The first wave was left fighting without reinforcements and took heavy casualties on the beach.