 One of the covert tactics of the Viet Cong is to use tunnels as infiltration or escape routes or munition storage areas and assembly points for major munitions. The tunnels may run beneath cities or towns, thus complicating their destruction. Project tunnels was initiated to evaluate two systems. One, a chemical for forcing the evacuation of the tunnels and if possible to maintain a residual deterrent. And the other, an explosive demolition system. This film deals only with the work of Edgewood Arsenal using riot control agent CS in the chemical system. The work with explosive demolition systems was accomplished by Picatinny Arsenal. Scale models of typical Viet Cong tunnels were constructed to determine which system may be the most effective in the evaluation tests. The tunnel complex was specified by the limited warfare laboratories. This tunnel was 375 feet in length and varied in depth to 13 feet below ground level. Based on a quick response to the need for tunnel denial, available potential systems were screened selected for final evaluation with the five following systems. Riot control hand grenades, dry agent dispersers, the Mars turbine generator with CS in solution, an experimental expendable launcher system which propels CS sub munitions. Mighty Might, a commercially available air blower of the agricultural sprayer and duster type, mounted on a pack board used with M7 type CS grenades. The Mighty Might costs less than $350. The gasoline powered blower weighs about 32 pounds including one gallon of fuel for two hours of operation. A plastic sheet was thrown over the tunnel entrance and the blower was placed at the edge of the opening. Dirt shoveled onto the edges of the sheet formed a seal. Four agent grenades were dropped into the tunnel at a rate of one grenade per two minute interval and the blower driven agent cloud began its traversal of the underground maze. Progress of the agent's movement throughout the complex could be gauged by watching the vent pipes. To accelerate the travel of the agent cloud, the vents were covered by bags as the agent was emitted from the vent pipe. However, leaving the vents uncovered does not interfere with the penetration of the tunnel. Chemical sampling devices along the tunnel route measured agent concentration at various points. In some of the tests, a wet blanket, a plastic sheet, and a plywood panel were placed in the tunnel to determine whether these barriers would retard the flow of agent. These barriers were all defeated by the agent cloud. In this particular film sequence, however, no barriers were employed. Observation of the blower and grenade method also brought out the fact that HC smoke grenades could be employed along with or instead of the riot control agent grenades to facilitate discovery of other entrances and vents of the tunnel system and to make the tunnels untenable. However, the smoke left no residual hazard. The tests proved that forced movement of the agent was a prerequisite to complete penetration of the tunnel. The mighty mite grenade system was the most effective because it was man-portable and propelled the agent into the innermost recesses of the tunnel complex. It was demonstrated that the agent cloud reached the first vent pipe within 30 seconds, a distance of 30 feet. In one minute and 35 seconds, the cloud had diffused 120 feet to the second vent and entrance B. After four minutes, penetration had advanced to vent number three, about 200 feet. At nine minutes, the agent cloud was observed at vents four and five, approximately 360 feet. Vent five was located at the munitions assembly room. Within 10 minutes after the actuation of the grenade and blower system, the entire tunnel complex had been traversed. These tests revealed that the commercial blower used with either the HC smoke grenade or the M7 type grenades provided the most complete penetration of tunnels and caves. Saturation of the tunnels with CS produced a residual hazard which rendered them untenable for a period in excess of three days. Next, a current report on three incapacitating chemical agent weapons, the multipoint source cluster, the handy-andy and the power pack. First, the multipoint source cluster, a keg-sized aerial cluster of 264 CS agent canisters, packed 33 to the bank in eight banks. A basic spelling charge initiates firing of the outer banks first, after which the succeeding internal banks are fired in sequence by the flash ignition of each preceding bank. The munitions are deliverable by nearly all army tactical aircraft and hand-activated by pulling a lanyard. They can be tossed on target from helicopter cabins. Or the cluster drop can be made by any tactical aircraft fitted with standard 14-inch shackles and equipped with special fixed wing assemblies. Ideal drop altitude is 500 feet when the cluster is toggled from fixed wing release by tactical aircraft flying at air speeds in excess of 200 miles an hour. The carrier is given clearance time between release and first bank ignition by a two-second delay in the lanyard fuse. The air burst and ground skittering effect of the canisters is boosted by the thrust of internal ignition caused by a pyrotechnic mix in the agent payload. This combination of air burst and secondary thrust on the part of the cluster's 264 agent canisters produce an effective CS agent cloud to cover an area of at least 10,000 square meters. Next, the handy-andy, a self-contained aluminum launch tube carrying its own 100 gram rubber grenade filled with a 60 gram pyromix and 40 grams of CS agent. The closure cap has a built-in firing pin and when slipped off and fitted to the other end of the tube it becomes the striker mechanism to ignite the launch propellant. Firing the handy-andy as is with one hand aiming the tube and hitting the striker cap with the other provides fair accuracy at distances up to 100 meters. A three-second delay fuse makes air bursts possible at ranges beyond 60 meters. Better launch accuracy can be given the handy-andy by removing the closure cap and fitting the aluminum tube into the breach of the M-8 flare pistol. Fired either way the agent grenade has the same three-second delay prior to the 15 seconds of burning time produced by a 60-40 combination of pyromix and agent. A cloud of CS agent about 15 feet in diameter is the result. Third and finally the power pack, a portable expendable multi-tube launcher designed for surface to surface CS assault preloaded with 64 canisters in a pack weighing less than 25 pounds. The unit has its own fuse system and launch platform packed in the canvas carrying case and can be set up and fired in a few seconds. There are four layers of canisters in each tube propelled by powder charges that get increasingly heavier according to their order of descending placement in the tube. The 40 gram weight of each round allows those in the top layer to be targeted at a mean distance of 50 meters. The second layer hits at 100, the third at 150 and the final layer 200 meters. The power packs four volleys provide a barrage pattern that delivers 64 agent canisters on target each of which is loaded with a 60-40 combination of pyromix and CS. Trained fuse, the firing cycle is completed in 10 seconds and covers an area of more than 4,500 square meters.