The massacre at My Lai and the Army's handling of it, dissected with an accomplished muckraking scalpel. The whens and wheres, definitive numbers of victims, communiques, missing files and broken careers come through: there is an accumulation of facts about the generals and officers who allegedly covered up the massacre, but we receive little new insight into the event or the Army itself. Based on the heretofore undisclosed findings of the Pentagon's Peers Commission, the emphasis is on the brass' effort to conceal the accumulated tarnish of genocide and war atrocities. The generals who putatively filed away My Lai (among them a past commander of West Point) and copiously distributed medals to Charlie and Bravo companies escape Calley's fate, of course, but are turned out to inconspicuous pastures. The stolid, substantial accretion of minutiae reaffirms Hersh's view of ""the army as an institution which. . . made so much of My Lai 4 inevitable,"" a view which reduces matters to military skulduggery and the eccentricities and aberrations of a cumbersome machine. The basic routines of ""gook hunting,"" ""pacification,"" and ""search-and-destroy,"" as well as free-fire zone bombings, remain outside the book's perimeter; but Hersh offers ample material for future historians trying to go beyond examination of the elephant's tail. Extensive chapter notes testify to Hersh's meticulous detective work.