David Stevenson's widely acclaimed history of World War I changes forever our understanding of that pivotal conflict. Countering the commonplace assumption that politicians lost control of events, and that the war, once it began, quickly became an unstoppable machine, Stevenson contends that politicians deliberately took risks that led to war in July 1914. Far from being overwhelmed by the unprecedented scale and brutality of the bloodshed, political leaders on both sides remained very much in control of events throughout. According to Stevenson, the disturbing reality is that the course of the war was the result of conscious choices -- including the continued acceptance of astronomical casualties. In fluid prose, Stevenson has written a definitive history of the man-made catastrophe that left lasting scars on the twentieth century. Cataclysm is a truly international history, incorporating new research on previously undisclosed records from governments in Europe and across the world. From the complex network of secret treaties and alliances that eventually drew all of Europe into the war, through the bloodbaths of Gallipoli and the Somme, to the arrival of American forces, and the massive political, economic, and cultural shifts the conflict left in its wake, Cataclysm is a major revision of World War I history.