Civil Wars: A History in Ideas by David Armitage Knopf, 349 pp., $27.95

The end of the world is on view at Philadelphia. Hurtling across a twenty-five-foot-wide canvas in the Pennsylvania Academy of the Fine Arts are the Four Horsemen of the Apocalypse. Together, Death, Pestilence, Famine, and War ravage the earth amid blood-red banners and what looks like cannon smoke. Warriors fall before their swords and spears, and women, children, and babies are slaughtered.

Benjamin West completed this version of Death on the Pale Horse in 1817, two years after the Battle of Waterloo. It is tempting therefore to see in the painting not only the influence of the book of Revelation, and perhaps the elderly West’s intimations of his own imminent mortality, but also a retrospective verdict on the terrible catalog of death and destruction that had been the Napoleonic Wars. Yet West’s original inspiration seems to have been another conflict. He first sketched out his ideas for Death on the Pale Horse in 1783, the concluding year of the American War of Independence. Bitterly divisive on both sides of the Atlantic, the war imposed strains on West himself. Pennsylvanian born and bred, he was a supporter of American resistance.

But in 1763 he migrated to Britain, and he spent the war working as a historical painter at the court of George III. So every day he served the monarch against whom some of his countrymen were fighting, knowing all the while that this same king was launching his own legions against Americans who had once been accounted British subjects. It was this tension that helped to inform West’s apocalyptic vision. More viscerally than most, he understood that the American Revolution was also in multiple respects civil warfare.

Tracing some of the histories of the idea of civil war, and showing how definitions and understandings of this mode of conflict have always been volatile and contested, is the purpose of this latest book by David Armitage. Like all his work, Civil Wars: A History in Ideas is concise, wonderfully lucid, highly intelligent, and based on a confident command of a wide range of printed sources. It is also ambitious, and divided into three parts in the manner of Julius Caesar’s Gaul. This seems appropriate since Armitage roots his account in ancient Rome. It was here, he claims, between the first century BCE and the fifth century CE, that lethal conflicts within a recognized society, a common enough experience in earlier eras and in other regions, began to be viewed and categorized as a distinctive form of war: bellum civile.

How this came to pass is the subject of Part One of the book. In Part Two, Armitage switches to the early modern era, which is here defined mainly as the seventeenth and eighteenth centuries, and shows how elite male familiarity with classical texts encouraged…