Many Vietnam memoirs have appeared in recent years, but not a single one has the humor, pathos, poignancy, and often sheer hilarity of John J. Gebhart's riveting LBJ'S Hired Gun. As Gebhart tells it, he was a "smart-mouthed college boy" who joined the Marines to see the world and "dust a few black pajamas for Uncle Sam." Two grueling tours of duty later (1965-1967) he returned home as a sergeant after surviving 240 combat missions (12 air medals)...