combat unit base camps. Interrogated prisoners and returnees revealed that as a rule personnel of organized Viet Cong combat units did not know the location of such tunnels. They might frequently reveal the general location, but information to locate the tunnels precisely had to come usually from local cadres and rear service personnel.

Extensive tunnel systems were found throughout the Iron Triangle- Thanh Dien forest area. Operation CEDAR FALLS demonstrated that patience is the primary weapon to use against an enemy hiding in tunnels: wait for him to run out of supplies or to get curious about where you are or what you are doing. It was some times necessary to flush the enemy out with tunnel rats or riot control agents or to seal and destroy the tunnels.

A tunnel rat team usually consisted of from six to ten men led by an officer or a noncommissioned officer. The individual in charge had the responsibility of drawing a sketch of the underground complex from information relayed from the team members within the tunnel. The lead element of the tunnel rat team was usually armed with a pistol equipped with a silencer (to fire in a tunnel without a silencer was to risk broken eardrums), hand telephone or "skull mike," flashlight, compass, and probe. One of the major problems in tunnel reconnaissance was that of communications. The skull mike (a transmitter strapped to the back of the skull) often became inoperative after a short period. In addition, the heavier U.S. communications wire which had to be used in lieu of the scarce lightweight Canadian assault wire added considerable weight and bulk to the team. Lack of fresh air was also a problem for the men when deep in the tunnels. The "Mighty Mite" (an air compressor with blower) or an auxiliary helicopter engine rigged with a 50 to 100 foot length of hose was often employed to force fresh air into the tunnel systems.

The job of a tunnel rat was difficult at best. Hot, dirty, and gasping for breath, he squeezed his body through narrow and shallow openings on all fours, never knowing whether the tunnel might collapse behind him or what he might find ahead around the next turn, and sensing the jolt of adrenalin at every sound. Surely this modern combat spelunker is a special breed.

The following is a description of the search and destruction of a large tunnel complex located in the triangle approximately six kilometers south of Rach Bap and about six hundred meters to the east of Route 14.

On 21 January a Viet Cong sympathizer was apprehended by the 168th Engineers and admitted having helped dig the under-