About this Unit
Underwater Demolition Team 4 (UDT-4) was one of the original Navy Underwater Demolition Teams formed during World War II. Established in 1943, UDT-4 played a crucial role in amphibious operations, specializing in reconnaissance, obstacle removal, and demolition ahead of Allied landings in the Pacific Theater. The team participated in significant operations including the invasions of Saipan, Tinian, and Guam, where their actions helped pave the way for main assault forces. After the war, UDT-4 continued to serve in various capacities until its eventual transition into the modern U.S. Navy SEAL Teams during the early 1960s.
Historical Facts
• Origins in WWII: Underwater Demolition Team 4 (UDT-4) was one of the original teams formed during World War II to clear obstacles ahead of amphibious landings, with its roots tracing back to the Navy Scouts and Raiders and Naval Combat Demolition Units (NCDU).
• Normandy Invasion: Members of UDT-4 participated in the D-Day landings at Normandy, helping clear beach obstacles under heavy fire to pave the way for Allied troops.
• Pioneers of Combat Swimming: UDT-4 operatives were among the first to develop and use combat swimming tactics, swimming to enemy beaches with explosives and hand tools to destroy obstacles.
• Pacific Theater Successes: UDT-4 played a critical role in Pacific campaigns, including the invasions of Saipan, Tinian, Guam, Leyte, and Okinawa, often working ahead of the main invasion forces.
• Innovative Equipment: The team helped develop and improve underwater breathing apparatus, fins, masks, and other gear, laying the groundwork for modern Navy SEAL equipment.
• Nickname: UDT-4 and other teams were often called “Frogmen” due to their aquatic operations and unique gear, a nickname that endures in popular culture.
• No Standard Uniforms: Early UDT-4 operators wore little more than swim trunks and sometimes face grease for camouflage, prioritizing speed and stealth over protection or regulation uniforms.
• First to Use Swimmer Delivery Vehicles: UDT-4 experimented with early swimmer delivery vehicles and “submersibles” for clandestine approaches to enemy beaches, a precursor to today’s SEAL Delivery Vehicles (SDVs).
• Post-War Legacy: After World War II, UDT-4 continued to serve during the Korean War and Cold War, eventually being absorbed into the U.S. Navy SEALs when they were created in 1962.
• Decorated Unit: UDT-4 members received numerous awards for bravery and effectiveness, including Presidential Unit Citations and individual medals for heroism under fire.
