Note 43 — PART V THE AIRLIFT

There is an interesting possibility as to why the mortars in the Horseshoe were never silenced. Fourteen years earlier, at Dien Bien Phu, the North Vietnamese used an ingenious method to protect their heavier siege mortars from air attacks and they may well have repeated it at Khe Sanh. The mortar crews selected a site on the slope of a hill, figured the elevation and deflection necessary to hit one specific target, and then dug a small tunnel at that precise angle into the side of the hill. The mortar was emplaced at the bottom of the tunnel with connecting caves which housed the gunners. When fired, the mortar rounds traveled up the shaft, sometimes as far as 50 feet before reaching the surface. The foliage was cleared away from the mouth of the tunnel so that the rounds did not hit the overhanging branches and detonate prematurely. Mortars emplaced in this manner were, of course, limited to only one target and, as far as the gunners in the Horseshoe were concerned, that target was 881S. When the siege was later broken and Marine units began to maneuver in the terrain surrounding the hill mass, they were never taken under fire by the 120mm mortars even though they did receive fire from smaller caliber weapons. Hill 881S, however, continued to be hit periodically by the 120mms.