“War in our time has been not merely a means of resolving inter-state disputes but also a vehicle through which the embittered, the dispossessed, the naked of the earth, the hungry masses yearning to breathe free, express their anger, jealousies, and pent-up urge to violence.” —John Keegan, A History of Warfare, 1993

During the twentieth century, the style of warfighting has changed many times. The first half of the century witnessed two world wars, multinational efforts that claimed millions of lives in the name of ending imperialism. These world wars were fought between grand alliances that committed conventional forces to the battlefield in hopes of wearing the other side down through attrition. The advent of the atom bomb and the coming of the nuclear age at the end of World War II made wars of attrition unnecessary. Nuclear weapons did not make conventional warfare obsolete, but they...