by C.D.B. Bryan
338 pages. Putnam. $10.95.
During the predawn hours of Feb. 18, 1970, on a jungle hilltop near the village of Chu Lai, South Viet Nam, an outgoing shell from a U.S. Army howitzer accidentally struck a treetop and exploded above the men of Charlie Company, 1st Battalion, Americal Division. Six were injured, two were killed. One of them was Michael Mullen, 25, the fifth generation of his family to farm the same fertile Iowa acreage. Michael was pierced by a small crescent of steel that tore a hole in his heart....