A Requiem for Crows — Dennis Foley

A carefree young man, shipped to Vietnam in the early sixties, faces treachery in the midst of battle in this novel by the author of Long Range Patrol.
 
With “a bit of James Dean in his walk, Elvis in his smile and Jerry Lee Lewis in his attitude,” Scotty Hayes is an unlikely candidate for the army. But the draft board is about to turn his world upside down. Two months after Scotty hitches a ride from Belton, Florida, to Fort Benning in Georgia with exactly thirty-nine dollars in his pocket, the president is assassinated. And Scotty is suddenly facing combat in Vietnam.
 
Now, Sergeant Hayes, accidental soldier, is at war against a new kind of enemy, fighting deadly AK-47 fire, the jungle, and treachery within his ranks. When a superior's cowardice plunges Scotty into a hot zone with his comrades' lives at stake, he must find an answer for the danger that threatens to engulf them all.