Vivid and meticulously detailed audits of what tipped the balance in a score of history's landmark battles. Seymour (Ordeal by Ambition, 1973)ranges widely through time, reconstructing conclusive engagements from Zama, the Carthaginian outpost where Rome's Scipio Africanus bested Hannibal in 202 B.C., through the Viet Minh's victory over French forces at Dien Bien Phu in 1954. Along the way, he assesses a host of other actions, including such storied clashes as those at Borodino, Bosworth, Gettysburg, Hastings, Isandhlwana, Saratoga, and Waterloo. Covered as well are less familiar encounters like those at Hattin, where an ill-advised Christian army marched to defeat at the hands of Saladin in mid-1187, and at Warsaw, whose defenders saved Central Europe from Bolshevik invaders during the summer of 1920. As promised, the author sheds considerable light on factors that turned the tide in his somewhat arbitrary selection of campaigns; he also puts such determinants into clear perspective. By way of example, Seymour shows how supply failures played a leading role in the beating taken by French troops in North Vietnam. In addition, he identifies contributory causes. As was the case with their British counterparts in Zululand, the French vastly underestimated the ability as well as strength of the native army opposing them, and they went into mortal combat with no clearly defined chain of command. Authoritative, illuminating accounts of turning-point battles with appeal for both military-history buffs and devotees of for-want-of-a-nail theory. The text (published last year in England) includes a generous measure of helpful maps and graphic material.