Overy brings vast knowledge to the title question and years of experience unraveling the knotted motivations of war. His approach is to separate the major drivers and motivations, and consider the ways each has contributed to organized conflict. They range from the impulses embedded in human biology and psychology, to the incentives to conflict developed through cultural evolution, to competition for resources--conflicts stirred by the passions of belief, the effects of ecological stresses, the drive for power in leaders and nations, and the search for security. The discussions show remarkable range, delving deep into the Neolithic past, through the twentieth-century world wars, and up to the current conflict in Ukraine. The examples are absorbing, from the Roman Empire's voracious appetite for resources to the impulse to power evident in Alexander the Great, Napoleon, and Hitler.    304 pages  hc

Kirkus Reviews - *Starred Review