Jack Snyder’s analysis of the attitudes of military planners in the years prior to the Great War offers new insight into the tragic miscalculations of that era and into their possible parallels in present-day war planning. By 1914, the European military powers had adopted offensive military strategies even though there was considerable evidence to support the notion that much greater advantage lay with defensive strategies. The author argues that organizational biases inherent in military strategists’ attitudes make war more likely by encouraging offensive postures even when the motive is self-defense.Drawing on new historical evidence of the specific circumstances surrounding French, German, and Russian strategic policy, Snyder demonstrates that it is not only rational analysis that determines strategic doctrine, but also the attitudes of military planners. Snyder argues that the use of rational calculation often falls victim to the pursuit of organizational interests such as autonomy, prestige, growth, and wealth. Furthermore, efforts to justify the preferred policy bring biases into strategists’ decisions-biases reflecting the influences of parochial interests and preconceptions, and those resulting from attempts to simplify unduly their analytical tasks.The frightening lesson here is that doctrines can be destabilizing even when weapons are not, because doctrine may be more responsive to the organizational needs of the military than to the implications of the prevailing weapons technology. By examining the historical failure of offensive doctrine, Jack Snyder makes a valuable contribution to the literature on the causes of war.