Tunnels Of Củ Chi, Ho Chi Minh City, Saigon, Vietnam

U.S. campaigns against the tunnels
The tunnels of Củ Chi did not go unnoticed by U.S. officials. They recognized the advantages that the Viet Cong held with the tunnels, and accordingly launched several major campaigns to search out and destroy the tunnel system. Among the most important of these were Operation Crimp and Operation Cedar Falls.
Operation Crimp began on January 7, 1966, with B-52 bombers dropping 30-ton loads of high explosive onto the region of Củ Chi, effectively turning the once lush jungle into a pockmarked moonscape. Eight thousand troops from the U.S. 1st Infantry Division, 173rd Airborne Brigade, and the 1st Battalion, Royal Australian Regiment combed the region looking for any clues of PLAF activity.