UDTs (Underwater Demolition Team) had their genesis following the U.S. Marine invasion of Tarawa. The invasion beaches were ringed with underwater coral formations hidden from the Marines. Landing craft slammed into the coral and took deadly fire from the Japanese. Many Marines drowned as they attempted to reach shore more than half a mile away.

It was obvious that submerged fortifications could prove disastrous for troops, landing craft and an entire military operation. In this same time period, plans were being finalised for the invasion of Normandy where it was known the coast was heavily fortified with underwater mines and obstacles designed to gut a landing craft. A new strategy was needed.

The idea of Frogmen was certainly not a new one. The British SBS had been founded in 1940 with all members trained as divers while Italians were well known for their underwater commandoes in WWI nicknamed “Uomini Rana”, Italian for “frog men”. The name stemmed from the unique, frog-like kicking style used by the commandoes.

The first major U.S. amphibious operation of WWII was launched in November 1942 when 400,000 men landed off of 890 ships in North Africa. This landing met with limited resistance as the British were already fighting the Germans. However, the military minds realised that there might be a need for operations to clear beaches in the future. Admiral Turner approached LCMR Draper Kauffman about the development of Underwater Demolition Teams (UDTs). At that time, Kauffman was in charge of the Mine Disposal School in Washington.

Kauffman was a graduate of the Naval Academy in 1933. He was captured by the Germans in Europe and later escaped. His first major assignment in the Pacific was to disassemble a 500 lb bomb that had hit Schofield Barracks during the bombing of Pearl Harbor. He later set up the Navy’s first bomb disposal school. Kauffman mulled over the idea of UDTs for quite a while and finally decided the best way to rid the beaches of obstacles was to send in men trained in handling explosives, thereby blasting the beaches clear for the landing crafts. He began to look for volunteers in the Navy Construction Battalion or CBs (later remained the See Bees) who were used to handling explosives. He later sought out Navy and Marine personnel who were rugged and had previous swimming experience. It was understood that all UDT members were volunteers and they could resign at any time.


The men were brought together in the summer of 1943 at Fort Pierce in Florida for six weeks of training. Additional training in Hawaii followed this. The theory was that a man is capable of about 10 times as much physical output as is normally assumed. Gruelling exercises were conducted in the ocean and the swamps with the alligators and snakes. The focus was on demolishing the obstacles that were expected at Normandy. Training was extensive and exhausting. Timing and teamwork were critical for each mission.

Many of the team members were from the West Coast and were seasoned watermen and surfers. One former WWII UDT member told of his occasional encounter with sharks in the ocean during training. “One day while swimming in very deep water, I happened to look up to see a six or seven foot shark coming along. I reached for my knife and it wasn’t there. For some reason I had forgotten it. I tried to act calm, saying over and over again that most sharks never bother anyone. Boy was I relieved when it disappeared into nowhere. I never forgot my knife again!”


He went on to describe how they would practice cruising in toward shore on rubber rafts loaded with explosives and then blowing up a reef. “Let me tell you, that when two or three tons of TNT goes off, it makes Old Faithful look like a pot of boiling water!” As a result of their training, the men were soon at home in the mud, noise, water and exhaustion.

The UDTs always functioned in small teams. Their apparel consisted of a pair of swimming trunks, fins, mask, a lead line to measure depths, coral shoes to walk on the sharp coral, a slate for taking notes, a life ring and a Hagansen pack. This explosive pack was for destroying a selected obstacle with limited shrapnel, hopefully protecting the diver. Later, when diving in colder oceans such as at Iwo Jima, the only insulation was a layer of grease applied to their skin.

This group worked hard but was never called upon. Then came Tarawa. From then on, the demand for UDTs exploded. Various training programs were developed at different bases, each with a different focus. Some teams trained extensively in reef and obstacle explosives while other became experts in reconnaissance, where they would sneak ashore and determine resistance levels of the enemy prior to an invasion.

UDT Marine Sign

This second group was not without their sense of humour. It has been said that UDTs would come ashore and doodle the famous “Kilroy was here” symbol on structures found ashore. I asked one of our WWII veteran frogmen about it and while he denied knowledge of that story, he replied that his friend in another UDT unit was known for posting small signs on the beach stating, “Army, USO that way”, with an arrow pointing up the beach! The teams also discovered that due to the slowing of bullets underwater, they could catch them in their bare hands. Many were brought back as souvenirs.

The UDTs were later involved in most of the subsequent battles of the Pacific as well as Europe, and Normandy. They were key to the success of Kwajalein, Tinian, Guam, Peleliu, Saipan, Philippines, Borneo, Iwo Jima and Okinawa, among others. Their mark on the success of WWII can never be overstated. On Guam, they removed over 930 obstacles in six days. A very small piece of the Navy, they never numbered more than 32 units and 3000 men. Thanks to the success of the UDTs, the Navy took the skills and team concept of an exceptionally well-trained small unit and developed the highly regarded Navy Seal program.

Before the Naval Demolition Project was established there were other units formed that developed legacy capabilities to accomplish what we now know as Naval Special Warfare. Two were formed at ATB Little Creek, Norfolk, Va., in August 1942 almost simultaneously. Each was to perform specific missions in Operation Torch, the Allied invasion of North Africa in November 1942, and yet it is doubtful that either knew about the other or their assigned tasks.


The Amphibious Scouts and Raiders (Joint) were formed to reconnoiter prospective landing beaches and also to lead assault forces to the correct beach under cover of darkness. The unit was led by Army 1st Lt. Lloyd Peddicord as commanding officer and Navy Ensign John Bell as executive officer. Navy chief petty officers and sailors came from the boat pool at ATB Solomons, and Army personnel came from the 3rd and 9th Infantry Divisions. These two groups were gathered at ATB Little Creek in late August, where they trained until embarking for Operation Torch in November. The Scout and Raider school was relocated to ATB Fort Pierce in February 1943, and in July it became an all Navy school reorganised to accomplish a training program code-named “Amphibious Roger.” Roger men were being trained for deployment to the Sino-American Cooperative Organisation (SACO) in China, where they became known as “Rice Paddy sailors.” Scout and Raider units and capabilities did not survive the postwar period.

During the same period, a specialised naval demolition team was formed with two naval Reserve officers and 17 enlisted men. All were U.S. Navy trained salvage divers. Their crash course at ATB Little Creek during August and September 1942 included demolitions, commando tactics, cable cutting, and rubber-boat training. Their single mission was to demolish a heavily cabled boom blocking the Wadi Sebou River so that USS Dallas(DD 199) could proceed up the river and train her guns on the Port Lyautey airdrome in preparation for attack by embarked Army Rangers. This was a hair-raising story of determination and success; however, the group was disbanded once it returned from Africa. Because they were Navy divers and because they were given training in demolitions, they have often been referred to as underwater demolition men, but they were not. Of interest, every man in this group was awarded the Navy Cross for his actions in this mission.


Post WWII, the UDTs operated on the coasts of North Korea during the Korean War, with their efforts initially focused on demolitions and mine disposal. Additionally, they accompanied SOK commandos on raids in the North to demolish railroad tunnels and bridges. The higher-ranking officers of the UDT frowned upon this activity because it was a non-traditional use of the Naval forces, which took them too far from the water line. Due to the nature of the war, the UDT maintained a low operational profile. Some of the better-known missions include the transport of spies into North Korea, and the destruction of North Korean fishing nets.

The Korean War was a period of transition for the men of the UDT. They tested their previous limits and defined new parameters for their special style of warfare. These new techniques and expanded horizons positioned the UDT well to assume an even broader role as the storms of war began brewing to the south in Vietnam.

The Navy entered the Vietnam War in 1958, when the UDTs delivered a small watercraft far up the Mekong River into Laos. In 1961, Naval advisers started training the South Vietnamese UDT. These men were called the Liên Đoàn Người Nhái (LDNN), roughly translated as the "soldiers that fight under the sea."

Later, the UDTs supported the Amphibious Ready Groups operating on South Vietnam's rivers. UDTs manned riverine patrol craft and went ashore to demolish obstacles and enemy bunkers. These Detachments operated throughout South Vietnam, from the Mekong Delta (Sea Float), The Parrot Beak and French canal AO's through I Corps and the Song Cui Dai Estuary south of Danang.


In the mid-1950s, the Navy saw how the UDT's mission had expanded to a broad range of "unconventional warfare", but also that this clashed with the UDT's traditional focus on swimming and diving operations. It was therefore decided to create a new type of unit that would build on the UDT's elite qualities and water-borne expertise, but would add land combat skills, including parachute training and guerrilla/counterinsurgency operations.These new teams would come to be known as the SEALs (which stood for SEa, Air, and Land). Initially there was a lag in the unit's creation until President John F Kennedy took office. Kennedy recognised the need for unconventional warfare, and supported the use of special operations forces against guerrilla activity. The Navy moved forward to establish its new wing and in January 1962, SEAL Team One was commissioned. The SEALs quickly earned a reputation for valor and stealth in Vietnam, where they conducted clandestine raids in perilous territory. Since then, teams of SEALs have taken on shadowy missions in strife-torn regions around the world, stalking high-profile targets such as Panama's Manuel Noriega and Colombian drug lord Pablo Escobar and playing integral roles in the wars in Iraq and Afghanistan.