This study examines what history suggests about the future possibilities and characteristics of war and the place that thinking about conflict deserves forming American strategy in the coming decades. The author offers a historical perspective to show that armed conflict among organized political groups has been mankind’s constant companion and that America must remain prepared to use its military power to deal with an unstable, uncertain, and fractious world. Williamson Murray shows that although aspects of human conflict will not change no matter what advances in technology or computing power may occur, the character of war is changing at an increasingly rapid pace, with scientific advances providing new and more complex weapons, means of production, communications, sensors, and myriad other inventions, all capable of altering the character of the battle space in unexpected fashions. He explains why the past is crucial to understanding many of the possibilities that lie in wait, as well as for examining the course of American strategy and military performance in the future and warns that the moral and human results of the failure of American politicians and military leaders to recognize the implications of the past are already apparent.