Which military group was primarily tasked with destroying underwater barriers and obstacles?

The Naval Combat Demolition Units (NCDUs) were specifically formed during World War II to address the critical need for clearing underwater obstacles and barriers. These units played a vital role during the amphibious assaults by engaging directly with enemy defenses to ensure safe passage for landing forces.

The NCDUs were trained in various techniques to locate, assess, and neutralize underwater mines, booby traps, and other obstructions that could impede an assault. Their operations were essential during significant landings, such as those at Normandy and in the Pacific theater, where underwater barriers posed substantial risks to both personnel and landing craft.

In contrast, while Navy SEALs today fulfill similar roles, they were not established until after WWII and their primary focus is broader, involving special operations beyond demolitions. The Office of Strategic Services (OSS) was primarily focused on espionage and unconventional warfare rather than direct demolition tasks. Marine reconnaissance, while also involved in intelligence gathering and direct action, does not have the specific mandate to clear underwater barriers like the NCDUs had during their operations. Thus, the NCDUs stand out as the distinct group responsible for this critical mission during the war.