John Plaster (The Ultimate Sniper), a retired Army major, served three tours with the secretive "Studies and Observation Group," aka SOG, during the Vietnam War-a background he has put to good use in this authoritative and insightful look at the now-defunct commando unit. Plaster does much to illuminate both this frequently misunderstood group and its extraordinary participants. Made up entirely of volunteers, SOG tackled a wide range of vital and dangerous duties, including missions deep into...