From the cover:
Mai Linh, in the northern Vietnamese province of Quang Tri, was the headquarters for a special Marine unit, the Combined Action Program. Their mission was to become integrated into village life and train the natives to fight against the Viet Cong. But for individual marines like Peter Vanderpool and Barry Marshall, the CAP company was a trap.
Instead of training the Vietnamese and pulling out according to plan, they found themselves in a clean-up unit. As the North Vietnamese troops moved in, they prepared for a mission that would stretch their endurance to the limit, and test their courage in the savagery of all-out war.