Underwater Demolition Team

The first week of November NCDU-11 was sent to England to start preparations for Operation Overlord. All told, the NCDUs had 34 teams in England for the invasion of Normandy. To prepare for D-day the NCDUs trained with the 146th, 277th and 299th Combat Engineers.[16] Each NCDU had 5 Army Combat engineers attached to it. In the beginning the first 10 NCDUs broke into three groups.[16] Initially they had no group Commander. The senior officer by rank was the head of group III, Lieutenant Smith (CEC). He assumed command in an unofficial capacity.[16] His group III worked on experimental demolitions and developed the Hagensen Pack.[16](an innovation that used 2.5-pound (1.1 kg) of tetryl placed into rubber tubes that could be twisted around obstacles)[17] As more teams arrived a NCDU Command was created. The NCDUs at Normandy were numbers: 11, 22–30, 41–46, 127–8, 130-42[16]

"NCDU 45"; Ensign Karnowski, Chief Carpenters Mate Conrad C. Millis, MMCB2 Lester Meyers and three gunners mates. The unit received a Presidential Unit Citation with Ens. Karnowski earning the Navy Cross & French Croix de Guerre with Palm, while MM2 Meyers received a Silver Star. Two men were wounded and one was killed

80-G-258013 At Morotai NCDU 21 with MacArthur's 7th Fleet makes a channel using 8 tons of explosives in a single blast. Debris was thrown 800 yards or nearly a half mile.

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 Scouts and Raiders spent weeks gathering information during nightly surveillance missions up and down the French coast. Replicas of the Belgian Gates were constructed on the south coast of England for the NCDUs to practice demolitions on. It was possible to blow a gate to pieces, but that only created a mass of tangled iron creating more of an obstacle. The NCDUs found that the best method was to blast the structural joints of a gate so that it fell down flat.

The NCDU teams (designated Demolitions Gap-Assault teams) would come in at low tide to clear the obstacles. Their mission was to open sixteen 50-foot (15 m) 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.[6] 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.[18] A few were temporarily attached to UDTs.[18] Later NCDUs 1-10 were combined to form Underwater Demolition Team Able.[18] 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.

The invasion of Tarawa in November 1943 nearly met disaster due to unseen obstructions in the water. Tarawa lies in eastern Micronesia and had an unusual neap tide leaving insufficient clearance for the Higgins boats (LCVPs) to get over the reef. The Amtracs carrying the first wave crossed the reef successfully. But the LCVPs carrying the second wave ran aground on the reef. The Marines had to wade several hundred yards to shore while wearing full packs, under heavy fire across treacherously uneven coral. Many drowned or were killed before making the beach. The first wave, fighting without reinforcements from the second wave, took heavy losses on the beach.

ChCarp. W. H. Achenson CEC at Silver Star award ceremony for UDT 1 action

Seabees in both UDT 3 & UDT 4 made these welcome signs for the U.S. Marine Corps on Guam.

The next operation was to be Kwajalein and the plan calling for night reconnaissance. However, Rear Admiral Turner did not want a repeat of Tarawa. He wanted to know about coral and any obstacles the Japanese may have emplaced. To find this out the men that Lt Crist had staged were used to form UDT 1 and UDT 2. The team commanders were Cmdr. E.D. Brewster (CEC) UDT 1 and Lt. Crist UDT 2 (Lt. Crist was replaced and made Ops officer because Admiral Conolly wanted a commander with combat experience).

UDT 1 was ordered to perform two daylight recons.[21] The missions were to follow the standard Fort Pierce procedure with each two-man team getting close to the beach in a rubber boat, wearing combat fatigues, boots, helmets, and life jackets, and make their observations. Team 1 found that the reef kept them from ascertaining conditions both in the water and on the beach. In keeping with the Seabee traditions of: (1) doing whatever it takes to accomplish the job and (2) not always following military rules to get it done, UDT 1 did both.

Ensign Lewis F. Luehrs and Seabee Chief Bill Acheson had anticipated that they would not be able to carry out the assignment following Fort Pierce protocol and had worn swim trunks beneath their fatigues.[21] Stripping down, they swam 45 minutes undetected across the reef returning with sketches of gun emplacements and other intelligence. Still in their trunks, they were taken directly to Rear Admiral Turner's flagship to report.[21] Afterwards, Rear Admiral Turner concluded that the only way to get this kind of information was to do what these men had done as individual swimmers, which is what he relayed to Admiral Nimitz. The planning and decisions of Rear Admiral Turner, Ensign Luehrs and Chief Acheson made Kwajalein a developmental day in UDT history, changing both the mission model and training regimen. Luehrs would make rank and be in UDT 3 until he was made XO of UDT 18. Acheson and three other UDT officers were posted to the 301st CB as blasting officers.[5] The 301st specialized in Harbor dredging. It saved UDT teams from blasting channels and Harbor clearance, but it required it's own blasters.

Admiral Turner ordered the formation of nine teams, six for VAC and three for III Amphibious Corps. Seabees made up the majority of the men in teams 1–9, 13 and 15. The Officers of those teams were primarily CEC[22] (Seabees). UDT 2 was sent to Roi-Namur where Lt. Crist would earn a Silver Star. UDTs 1 and 2 were decommissioned upon return to Hawaii with the men transferred to UDTs 3, 4, 5, and 6. Admiral Turner ordered the formation of nine teams, three for III Amphibious Corps and six for V Amphibious Corps(in all teams 3-11). As more NCDUs arrived in the Pacific they were used to form even more teams. UDT 15 was an all NCDU team.

It became obvious more men were needed than the NCDUs would supply and Cmdr. Kauffman was no longer recruiting Seabees, so Admiral Nimitz put out a call to the Pacific Fleet for volunteers. They would form three teams, UDT 14 would be the first of them. Recruiting was such an issue that three Lt Cmdrs where transferred from USN Beach Battalions to command UDTs 11, 12, 13 that had no background in demolition.

Admiral Turner requested the establishment of the Naval Combat Demolition Training and Experimental Base at Kihei independent of Fort Pierce, expanding upon what had been learned from UDT 1 at Kwajalein. Operations began in February 1944 with Lt. Crist the first head of training. Most of the procedures from Fort Pierce were changed, replaced with an emphasis on developing swimmers, daylight reconnaissance, and no lifelines. The uniform of the day changed to diving masks, swim trunks, and a Ka-bar, creating the UDT image as "Naked Warriors"(swim-fins were added after UDT 10 introduced them).

Lt. Crist was head of training a very short time before he was made commander of UDT 3. In April, Lt. Cmdr. Kauffman was transferred from Fort Pierce to command UDT 5 and then serve as "Senior Staff Officer, Underwater Demolition Teams, Amphibious Forces", as well as be the "Underwater Demolition Training Officer, Amphibious Training Command".

At Saipan and Tinian UDTs 5, 6, & 7 were given the missions: day time for Saipan and night for Tinian. At Saipan UDT 7 developed a method to recover swimmers on the move without making the recovery vessel a stationary target.

For Guam UDTs 3, 4, & 6 were the teams assigned. When it was over the Seabee dominated teams had made naval history.[23] For the Marianas operations Admiral Turner recommended over sixty Silver Stars and over three hundred Bronze Stars with Vs for UDTs 3-7[23] That was unprecedented in U.S. Naval/Marine Corps history.[23]

For UDTs 5 and 7, all officers received silver stars and all the enlisted received bronze stars with Vs for Operation Forager (Tinian).[24] For UDTs 3 and 4 all officers received a silver stars and all the enlisted received bronze stars with Vs for Operation Forager (Guam).[24] Admiral Conolly felt the commanders of teams 3 and 4 (Lt. Crist and Lt. W.G. Carberry) should have received Navy Crosses.[24] Teams 4 & 7 also received Naval Unit Commendations.

UDTs 6, 7, and 10 drew the Peleliu[25] assignment while UDT 8 went to Angaur. The officers were almost all CEC and the enlisted were Seabees.[26]

At formation UDT 10 was assigned 5 officers and 24 enlisted that had trained as OSS Operational Swimmers.(Maritime Unit: Operational Swimmer Group II) They were led by a Lt. A.O. Chote Jr., who became UDT 10's commanding officer.The men were multi-service: Army, Coast Guard, Marine Corps and Navy.[27][28] but, the OSS was not allowed to operate in the Pacific Theater. Admiral Nimitz needed swimmers and did approve their transfer from the OSS to his operational and administrative control. Most of their OSS gear was stored as it was not applicable to UDT work however, their swimfins came with them. The other UDTs quickly adopted them.

UDT 14 was the first all-Navy team (one of three from the Pacific fleet) even though its CO and XO were CEC and some of Team Able was incorporated. In the Philippines Leyte Gulf UDTs 10 & 15 reconnoitered beaches at Luzon, teams 3, 4, 5, & 8 were sent to Dulag and teams 6, 9, & 10 went to Tacloban.

When UDT 3 returned to Maui the team was made the instructors of the school.[29] Lt Crist was again made Training Officer. Under his direction training was broken into four 2-week blocks with an emphasis on swimming and reconnaissance.[29] There were classes in night operations, unit control, coral and lava blasting in addition to bivouacking, small unit tactics and small arms.[29] Lt Crist would be promoted to Lt Cmdr and the team would remain in Hawaii until April 1945.[29] At that time the Seabees of UDT 3 were transferred to Fort Pierce to be the instructors there.[29] In all they would train teams 12 to 22.[29] Lt. Cmdr. Crist would be sent back to Hawaii.

D-minus 2 at Iwo Jima UDTs 12, 13, 14, and 15 reconnoitered the beaches from twelve LCI(G) with just one man wounded. They did come under intense heavy fire that sank three of their LCI(G) with the others seriously damaged of disabled. The LCI(G) crews suffered more than the UDTs with the skipper of one boat earning a Medal of Honor. The next day a Japanese bomb hit UDT 15's APD, USS Blessman killing fifteen and wounding 23. It was the largest loss suffered by the UDTs during the war.

On D-plus 2 the beachmaster requested help. There were so many broached or damaged landing craft and the beach was so clogged with war debris that there was no place for landing craft to get ashore. Lt Cmdr. E. Hochuli of UDT 12 volunteered his team to go deal with the problem and teams 13 and 14 were ordered to go with.[30] Lt Cmdr. Vincent Moranz of UDT 13 was "reluctant, and radioed that his men ... were not salvage-men.[30] It is reported that Capt. (Bull) Hanlon, Underwater Demolition Operations Commanding Officer radioed back that he didn't want anything salvaged, he wanted that beach cleared."[30] The difference in attitude between Hochuli and Moranz would be remembered in the unit awards.

The three teams worked for five days clearing the waters edge. While the teams all did the same job under the same conditions[30] the Navy gave them different unit awards: UDT 12 a PUC, UDT 14 a NUC and UDT 13 nothing. The USMC ground commanders felt that every man that set foot on the island during the assault had an award coming. The Navy did not share this point of view, besides UDT 13 not a single USN beach party received a unit award either. On D-plus 2, when the UDTs set foot on beaches that were under a USMC assault, any unit award they received should have come under the USMC award protocol. The USMC Iwo Jima PUC/NUC was a mass award with the PUC going to assault units and the NUC going to support units.

UDTs also served at Eniwetok, Ulithi, Leyte, Lingayen Gulf, Zambales, Labuan, and Brunei Bay. At Lingayen UDT 9 was aboard the USS Belknap when she was hit by a Kamikaze. It cost the team one officer, 7 enlisted, 3 MIA and 13 wounded.

Beach reconnaissance map of Okinawa by Team 7

The largest UDT operation of WWII was the invasion of Okinawa, involving teams 7, 11, 12, 13, 14, 16, 17,[31] and 18 (nearly 1,000 men). All prior missions had been in warm tropic waters but, the waters around Okinawa were cool enough that long immersion could cause hypothermia and severe cramps. Since thermal protection for swimmers was not available, UDTs were at risk to these hazards working around Okinawa.

Operations included both real reconnaissance and demolition at the landing beaches, and feints to create the illusion of landings in other locations. Pointed poles set into the coral reef protected the beaches on Okinawa. Teams 11 and 16 were sent in to blast the poles. The charges took out all of UDT 11's targets and half of UDT 16's. UDT 16 aborted the operation due to the death of one of their men; hence, their mission was considered a failure. UDT 11 went back the next day and took out the remaining poles after-which the team remained to guide landing-craft to the beach.

By wars end 34 teams had been formed with teams 1–21 having actually been deployed. The Seabees provided half of the men in the teams that saw service. The U.S. Navy did not publicize the existence of the UDTs until post war and when they did they gave credit to Lt. Commander Kauffman and the Seabees.[32]

During WWII the Navy did not have a rating for the UDTs nor did they have an insignia. Those men with the CB rating on their uniforms considered themselves Seabees that were doing underwater demolition. They did not call themselves "UDTs" or "Frogmen" but rather "Demolitioneers" which had carried over from the NCDUs[33] and LtCdr Kauffmans recruiting them from the Seabee dynamiting and demolition school. UDTs had to meet the military's standard age guidelines, Seabees older could not volunteer.

In preparation for the invasion of Japan the UDTs created a cold water training center and mid-1945 UDTs had to meet a new physical standard. UDT 9 lost 70% of the team to this change. The last UDT demolition operation of the war was on 4 July 1945 at Balikpapan, Borneo. The UDTs continued to prepare for the invasion of Japan until VJ Day when their role in the Pacific came to an end. With the draw-down from the war two half-strength UDTs were retained, one on each coast: UDT Baker and UDT Easy.

LCDR Edward P. Clayton, (back to camera) Commanding Officer UDT 21, receiving the first sword surrendered to an American force in the Japanese Home islands, from a Japanese Army Coastal Artillery Major (opposite Clayton), at Futtsu-misaki Point, across Tokyo Bay from Yokosuka Naval Base, 28 August 1945. When word of this circulated LCDR Clayton was ordered to give up the sword. Protocol dictated that General MacArthur should receive the first surrendered sword.

On 20 August 1945 USS Begor embarked UDT 21 at Guam as a component of the U.S. occupation force heading for Japan.[34] Nine days later UDT 21 became the first U.S military unit to set foot on Japanese home soil when it reconned the beaches at Futtsu-misaki Point in Tokyo Bay.[34] Their assessment was that the area was well suited for landing U.S. amphibious forces. UDT 21 made a large sign to greet the Marines on the beach. Team 21 was all fleet and the sign said greetings from "USN" UDT 21. The next day Begor took UDT 21 to Yokosuka Naval Base.[34] There the team cleared the docks for the first U.S. warship to dock in Japan, USS San Diego.[34] The team remained in Tokyo Bay until 8 Sept when it was tasked with locating remaining Kamikaze and two-man submarines at Katsura Wan, Uchiura Wan at Suruga Bay, Sendai, Onohama Shipyards and Choshi.[34] Orders arrived for Begor to return the team to San Diego on 27 September.[34]

From 21–26 September UDT 11 was at Nagasaki and reported men getting sick from the stench.[35]

With the war over thousands of Japanese troops remained in China. The issue was given to the Marine's III Marine Amphibious Corps. UDT 9 was assigned to Operation Beleaguer to recon the landings of the 1st Marine Division at Taku and Tsingtao the first two weeks of October 1945.[36] On their way to China the Navy had UDT 8 carry out a mission at Jinaen, Korea 8–27 September 1945.[36] When UDT 9 arrived back in the States it was made one of the two post-War teams and redesignated UDT Baker.[36]

UDT 8 was also sent to China and was at Taku, Chefoo, and Tsingtao.[37]

Bikini atoll was chosen for the site of the nuclear tests of Operation Crossroads.

"In March 1946, Project Y scientists from Los Alamos decided that the analysis of a sample of water from the immediate vicinity of the nuclear detonation was essential if the tests were to be properly evaluated. After consideration of several proposals to accomplish this, it was finally decided to employ drone boats of the type used by Naval Combat Demolition Units in France during the war".[38]

UDT Easy, later named UDT 3, was given the designation TU 1.1.3 for the Operation and was assigned the control and maintenance of the drone boats. On 27 April, 7 officers and 51 enlisted men embarked the USS Begor at the Seabee base Port Hueneme, CA,[38] for transit to Bikini. At Bikini the drones were controlled from the Begor . Once a water sample was taken the drone would return to the Begor to be hosed down for decontamination. After a Radiation Safety Officer had taken a Geiger counter reading and the OK given, the UDTs would board with a radiation chemist to retrieve the sample.[39] Begor came to have the reputation as the most contaminated boat in the fleet.[39]

A major issue afterwards was the treatment of the dislocated natives. In November 1948, the Bikinians were relocated to the uninhabited Island of Kili, however that island was located inside a coral reef that had no channel for access to the sea.[40] In the spring of 1949, the Governor of the Trust Territories, Marshall Group requested the U.S. Navy blast a channel to change this.[40] That task was given to the Seabees on Kwajalin whose CO quickly determined this was actually a UDT project.[40] He sent a request to CINCPACFLT who forwarded it to COMPHIBPAC.[40] This ultimately resulted in the sending of UDT 3 on a Civic action program that turned out better than politicians could have hoped. The King of the Bikinians held a send off feast for the UDTs the night before they departed.[40]

Even though no combat operations seemed likely, the UDTs continued to research new techniques for underwater and shallow-water operations. One area was the use of SCUBA equipment. Dr. Chris Lambertsen had developed the Lambertsen Amphibious Respiratory Unit (LARU), an oxygen rebreather, which was used by the Maritime Unit of the OSS. In October 1943, he demonstrated it to LCDR Kauffman, but was told there was no place in current UDT operations for this radically new device.[41][42] Dr. Lambertsen and the OSS continued to work on closed-circuit oxygen diving and combat swimming. When the OSS was dissolved in 1945, Lambertsen retained the LARU inventory. He later demonstrated the LARU to Army Engineers, the Coast Guard, and the UDTs. In 1947, he demonstrated the LARU to LCDR Francis "Doug" Fane, then a senior UDT commander.[41][43] LCDR Fane was enthusiastic for new diving techniques. He pushed for the adoption of rebreathers and SCUBA gear for future operations, but the Navy Experimental Diving Unit and the Navy Dive School, which used the old "hard-hat" diving apparatus, declared the new equipment be too dangerous. Nonetheless, LCDR Fane invited Dr. Lambertsen to NAB Little Creek, Virginia in January 1948 to demonstrate and train UDT personnel in SCUBA operations. This was the first-ever SCUBA training for Navy divers. Following this training, LCDR Fane and Dr. Lambertsen demonstrated new UDT capabilities with a successful lock-out and re-entry from USS Grouper, an underway submarine, to show the Navy's need for this capability. LCDR Fane then started the classified "Submersible Operations" or SUBOPS platoon with men drawn from UDT 2 and 4 under the direction of Lieutenant (junior grade) Bruce Dunning.[41][44]

LCDR Fane also brought the conventional "Aqua-lung" open-circuit SCUBA system into use by the UDTs. Open-circuit SCUBA is less useful to combat divers, as the exhausted air produces a tell-tale trail of bubbles. However, in the early 1950s, the UDTs decided they preferred open-circuit SCUBA, and converted entirely to it. The remaining stock of LARUs was supposedly destroyed in a beach-party bonfire. Later on, the UDT reverted to closed-circuit SCUBA, using improved rebreathers developed by Dr. Lambertsen.

It was at this time that the UDT, led by LCDR Fane, established training facilities at Saint Thomas in the Virgin Islands.[45]

The UDT also began developing weapons skills and procedures for commando operations on land in coastal regions. The UDT started experiments with insertion/extraction by helicopter, jumping from a moving helicopter into the water or rappelling like mountain climbers to the ground. Experimentation developed a system for emergency extraction by plane called "Skyhook". Skyhook utilized a large helium balloon and cable rig with harness. A special grabbing device on the nose of a C-130 enabled a pilot to snatch the cable tethered to the balloon and lift a person off the ground. Once airborne, the crew would winch the cable in and retrieve the personnel though the back of the aircraft. This technique was discontinued for training purposes after the death of a SEAL at NAB Coronado on a training lift. The teams still utilize the Skyhook for equipment extraction and retain the capability for war if an extreme situation requires it.