Before there were the Navy SEALs, there were the Underwater Demolition Teams (UDTs) of World War II in the Pacific. UDTs were in charge of reconnaissance of the shoreline prior to an amphibious invasion. They would reconnoiter the lay of the beaches and offshore waters and be on the lookout for any natural or manmade obstructions that would hinder landing craft. They would then use explosives to demolish any obstacles.
Although the UDTs were preceded by the Navy Scouts and Raiders and the Naval Combat Demolition Units (NCDUs) in the European Theater, the need for a Pacific equivalent became obvious during the invasion at Tarawa in November 1943, when Marines became stranded on reefs that aerial reconnaissance had misjudged to be deep enough for landing craft. The Marines were forced to wade a thousand yards to shore, and some drowned and others were killed by enemy fire. This established the necessity of human surveillance of the shore waters before an invasion.
In the early days of the UDTs, members worked in the water in full fatigues and shoes, but real-world battle conditions showed the need for a greater emphasis on swimming, and UDT members began to wear swim trunks and fins, becoming the Navy’s elite combat swimmers. The 34 teams were involved in amphibious invasions across the Pacific, including in Saipan, Tinian, the Philippines, Iwo Jima, Guam, and Okinawa—just to name a few.
You can find thousands of mentions of UDTs on Fold3, especially in the WWII War Diaries. Below are examples of just a few of the types of information you can find about UDTs on Fold3:
- General explanation of the pre- and post-assault work of UDTs
- Description of pre-assault tasks of a UDTs at Palau
- Description of post-assault tasks of UDTs at Palau
- UDT casualty during invasion of Okinawa
- Description of UDT pre-assault reconnaissance for Leyte landings
- Suggestions for improving performance of UDTs based on experiences on Angau
- Praise for UDTs at Leyte
- Photos of explosions caused by UDTs clearing reefs for landing crafts
Do you have any family members who served on an Underwater Demolition Team? Tell us about them! Or search for more info on UDTs on Fold3.