The Underwater Demolition Teams of the Pacific

Amphibious warfare, a critical component of military strategy, faced significant challenges during the early 20th century. Failures like the Gallipoli Campaign during World War I underscored the need for innovative techniques to improve amphibious landings. By the Second World War, the United States was determined to overcome these obstacles, particularly in the Pacific Theater. This determination gave rise to the creation of the Underwater Demolition Teams (UDTs), which became instrumental in ensuring the success of amphibious operations.

The disastrous Battle of Tarawa in November 1943 highlighted the dangers of unprepared landings. Naval amphibious craft struck uncharted coral reefs, leading to significant casualties. This tragedy prompted Admiral Kelly Turner, Commander of the 5th Amphibious Force, to establish specialized teams to ensure safe landings. These teams were initially composed of 180 men stationed at the Waimanalo Amphibious Training Base on Oahu.

This group would later form the foundation of the Underwater Demolition Teams, tasked with clearing obstacles, both natural and man-made, from beaches and coastal waters to facilitate safe landings.

The first UDT operations began with reconnaissance and demolition missions. Members underwent rigorous training, including swimming, demolition, and small-boat handling. Inflatable boats allowed them to approach shallow waters quickly, while their missions required stealth and precision.

One pivotal mission occurred during the planning for the invasion of Kwajalein in the Marshall Islands. Two Seabees from UDT 1, Ensign Lewis F. Luehrs and Chief Bill Acheson, conducted a daring daylight reconnaissance by swimming across coral reefs. Their findings directly influenced the planning of future amphibious assaults and emphasized the importance of strong swimming skills.

From then on, UDT members were trained as swimmers equipped with minimal gear: swim trunks, diving masks, and fins. This streamlined appearance earned them the nickname “Naked Warriors.”

The Kwajalein mission set a precedent for UDT operations. By navigating coral reefs and scoping enemy defenses, the teams ensured the safety of subsequent landings. This success established the value of underwater reconnaissance and demolition in amphibious warfare.

Underwater Demolition Teams played critical roles in securing beaches for major landings in Peleliu, Guam, and the Philippines. Their ability to adapt to new challenges—such as clearing debris and detecting enemy traps—proved vital to the success of Allied operations.

The mission at Iwo Jima demonstrated the versatility and resilience of the UDTs. Teams successfully cleared debris from beaches despite suffering casualties. UDT 15, operating from USS Blessman (APD-48), experienced one of the unit’s heaviest losses when a Japanese bomber attack killed 15 men and injured 23. However, their efforts allowed for a smooth landing operation, cementing their legacy as indispensable assets in amphibious warfare.

The invasion of Okinawa was the largest UDT operation of World War II, involving nearly 1,000 men from multiple teams. They faced harsh conditions, including cold waters and Japanese defenses embedded in coral reefs. Despite these challenges, their reconnaissance and demolition efforts paved the way for the invasion force.

Following World War II, the need for large-scale amphibious landings diminished, and the number of UDTs was halved. However, their role in shallow-water operations continued to evolve. By integrating SCUBA equipment and refining their tactics, the teams adapted to new military challenges.

UDTs remained active during the Korean and Vietnam conflicts, further solidifying their importance in modern warfare. Their legacy lives on as the forerunners of the US Navy SEALs, the elite special operations force renowned for their versatility and combat skills.

The “Naked Warrior” statue at the National Navy SEAL Museum commemorates the courage and contributions of the Underwater Demolition Teams. These pioneers set the standard for modern special operations, combining innovation, resilience, and bravery to achieve their mission objectives.

The Underwater Demolition Teams of the Pacific exemplify the ability to adapt and innovate under pressure. Born from the lessons of past failures, these teams played a pivotal role in the Allied success during World War II. Their contributions to amphibious warfare not only ensured victory in the Pacific Theater but also laid the foundation for the modern Navy SEALs, continuing a legacy of excellence in military operations.