The country's wars in Iraq and Afghanistan, its interventions around the world, and its global military presence make war, the military, and militarism defining features of contemporary American life. The armed services and the wars they fight shape all aspects of life--from the formation of racial and gendered identities to debates over environmental and immigration policy. Warfare and the military are ubiquitous in popular culture.

At War offers short, accessible essays addressing the central issues in the new military history--ranging from diplomacy and the history of...