The Viet Cong were well known for their devious jungle ambushes and cruelly ingenious booby traps. But one of the enemy’s deadliest—and stealthiest—techniques was to burrow in underground tunnels deep beneath the earth’s surface and launch attacks from the cover of dark and labyrinthine caverns. The Americans and their allies who took on the gruesome task of rooting out and defeating these hidden foes earned the humble but proud nickname of “tunnel rats.” Yet, in their first large-scale encounter with underground enemies at Cu Chi, the “tunnel rats” and their fellow soldiers were far from prepared for the horrifying dangers that lurked below them.
Operation Crimp, undertaken by U.S. and Australian forces in Binh Duong Province, South Vietnam, from Jan. 8-14, 1966, was the largest search and destroy action during the Vietnam War for its time. Maj. Gen. Jonathan O. Seaman, commander, 1st Infantry Division, was the overall allied leader. Combat units included 8,000 soldiers from the 1st Infantry Division, composed mainly of troops from the 1st Infantry Division’s 173rd Airborne Brigade and the 3rd Brigade. The 1st Battalion, Royal Australian Regiment, operating as part of the 173rd, played a significant role in the operation. The mission, according to the After-Action Report written by Col. William D. Brodbeck, commander of 3rd Brigade, and staff member 2nd Lt. Leo J. Mercier, was to “strike at the very heart of the Viet Cong [VC] machine in Southern RVN [Republic of Vietnam], the notorious ‘Hobo Woods’ Region in Binh Duong Province, just West of the fabled ‘Iron Triangle’ believed to be the…headquarters of the Viet Cong Military Region 4” (within the area U.S. forces designated the III Corps Tactical Zone).
Unsuspecting U.S. and Australian forces would literally step onto a formidable tunnel network, which extended more than 150 miles from the outskirts of Saigon all the way to the Cambodian border. The communists began digging these tunnels under the jungles of South Vietnam in the late 1940s while fighting the French. In the late 1950s
