Sunday, November 9, 2008

Cu Chi Tunnels - Part 4: Tunnels' Defense

This is the fourth installment on the Cu Chi tunnels, a collection of quotations from the book by Mangold & Penycate (1985). This installment focuses on how the tunnels were defended; mostly from Chapter 10: Stop the Americans! 
(For diagrams of typical tunnel systems, see here ... here ... and here.)

"[The] tunnels did need a defense system; they could not be left unprotected at the mercy of every GI foot patrol that stumbled upon a tunnel entrance or telltale ventilation shaft. The slow development of a tunnel defense strategy eventually owed much to Captain Linh's careful observations of the Americans during Operation Crimp.

"'They marveled at everything they saw,' he said, 'everything seemed strange and new to them - the jungle, the fruits, the water buffalo, even the chickens. Again and again they would stop and stare, even pick things up. Not only were they easy targets for our snipers, but I realized the best way to kill them was with more booby traps. After Crimp, we made more and more of them. I was sure they would work well for us.'

"[The homemade booby-trap business began to boom. Those with access to explosive powder, detonators, and a crude tunnel workshop, produced first and foremost, the DH-5 or DH-10 mine. These were modeled on the successful American claymore mine, and were to be used primarily against the American light armored tracks and half-tracks, and inevitably against unwary infantrymen. They were detonated either by pressure or - and this was a surprise - by command (remote-detonated)." (p. 109)

"The DH-5 and DH-10 were made out of crude steel, shaped like a saucer and containing five or ten pounds of high explosive. The mines stood on bipods pointing directionally, or they would lie buried a few inches underground. They inflicted dreadful injuries. [...]

"Tunnel rat Lieutenant David Sullivan ... recalled a particularly devious Viet Cong booby trap. A tunnel entrance would be exposed to lure the Americans. When a rat tem was sent down to investigate, the guerrillas in the tunnel knew that other GIs would gather round the entrance for communication or on guard. A claymore mine hidden in a nearby bush would then be detonated by wire from inside the tunnel. Sullivan lost several men like that: The VC waited until they heard the rats in the tunnel and then blasted the men still on the surface. In the confusion, the rats aborted the search and the guerrillas escaped into the tunnel system.

"One of the most feared variants of the DH-10 was the notorious Bouncing Betty, conical, with three prongs jutting out of the soil. When a foot struck a prong, a small charge was detonated, which shot the mine into the air about three feet, where it then exploded, showering shrapnel at groin level.

"For sheer ingenuity in adapting to local warfare conditions, a guerrilla farmer from the Cu Chi village of Nhuan Duc was to win the top award. To Van Duc invented a helicopter booby trap. It was known as the cane-pressure mine and for a while it was a successful (and to the Americans, quite baffling) answer to the problem of how to destroy the helicopters that brought troops and supplies into the jungle. [...]

"Mindful of the simple physical principle that the blades of a helicopter create a considerable downdraft, the farmer (To Van Duc) suggested placing DH-10 mines at the TOPS of trees in an area where the helicopters could be expected to fly fairly low, or one to which they could be lured to fly low for surveillance. A highly sophisticated friction fuse was connected to the branches of the tree or fairly tall bush, which bent under the helicopter's downdraft, detonating the mine, which then exploded under the machine. " (p. 110-111)

"At the other end of the evolutionary scale of weapons were those that owed more to the War of the Roses than to the high-tech was in Vietnam. There was the crossbow and arrow ... Historically cotemporaneous was a ... heavy mud ball with spiked bamboo stakes sticking out of it. This was attacked to a tree by a seemingly innocuous jungle vine. When freed by the tripwire, the ball swung hard across the track.

"Then there was the coconut mine, a hollowed-out nut packed with explosive powder and then covered by a rock as the missile - not lethal but scary. Or there was the bamboo mine. This was large bamboo joint, cleaned out and filled with nuts, bolts, broken glass or scrap metal, together with a small amount of plastic explosive or powder explosive. A friction fuse operated by a tripwire detonated this package.

"The most common ... booby trap was the wired grenade, used in tunnel entrances or in the tunnels themselves. [...] On jungle tracks and paths near the tunnels a favorite tactic was to place the grenade, with the safety pin removed, inside an appropriate tin can. A pull on the tripwire extracted the grenade from the can, which then automatically primed itself and exploded. [...]

"And there was the infamous punji stick traps around all the tunnels. Sometimes the Viet Cong dug tiger-trap pits; if a GI fell into one, he became impaled on the spikes. The trap was kept to reasonable size so that it could easily be camouflaged with twigs and foliage. but its depth was sufficient so that the victims foot would descend with enough force for the stakes to pierce ... the GI's jungle boot. A more sophisticated version had stakes buried in the wall of the pit, but facing downward, making extraction of the foot even more painful. Sometimes the sticks were smeared with excrement to aid infection, sometimes with a poison the VC simply called Elephant's Trunk, which they claimed caused death within twenty minutes of entering the bloodstream. " (p. 112-114)

"Inside the tunnels there were occasionally false walls, thinly plastered with clay, on the other side of which waited Viet Cong with bamboo spears. As a tunnel rat (American soldier) made his way slowly forward, the VC would spy through a hole in the false wall and spear [him]. [...]

"Booby traps and ambushes took a disproportionately high toll among infantrymen and remained a source of great anxiety to military tacticians in Vietnam. Throughout the war, booby traps were responsible for 11% of all American deaths, and 17% of all wounds.

"Real damage was often caused by the high rate of wound infection. [...] The ... booby traps inside and just outside the tunnels generated sufficient fear among the ordinary grunts to seriously affect their military effectiveness. A high-tech infantry that usually fought only by day and was helicoptered out by night was not necessarily going to go out of its way to discover long tunnel complexes. Everyone knew about the booby traps. And what the grunt eye did not see on patrol, no officer's heart was going to grieve about.

"In a revealing study conducted by Lt. General Julian J. Ewell, former commander of the II Field Force in Vietnam, it was shown that at least half the booby traps found by the 9th Division's GIs had been found by detonation - in other words, the men had set them off. 46% of the resultant casualties were multiple, caused by the bunching of troops, who just did not know any better. In 1969, booby traps were the single most important casualty source in the 9th Division. [...]

"If the tunnels' outer defenses failed to deter, the next line of defense was the so-called spider hole. Spider holes were superbly camouflaged pits, dug to shoulder depth near each of the three tunnel entrances, and linked by short communications tunnels to the main tunnel. One, sometimes two, Viet Cong snipers stood, perfectly protected, and shot at intruders; when it became too dangerous to stay, they scuttled through the communication tunnel back into the main tunnel complex. No sophisticated detection or weapons system could easily or mechanically find, fix, and destroy the ubiquitous spider-hole sniper. He could be (and frequently was) mortared, shelled by artillery, napalmed, or besieged by tank. But the longer he fought, the more he fulfilled his primary function, which was to engage large numbers of the enemy and keep them busy, distracting them from the real prize, the tunnel complex over which he kept his lonely vigil." (p. 115-116)

1 comment:

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