The Face of Battle is ostensibly a broad survey of military history; however, digging a little deeper, it is also an exposition on the structure and purpose of history itself.

John Keegan starts the novel by analyzing war's historical tradition. He points out certain shortcomings in the literary form of the "battle piece," arguing that it fails to take into account war's necessary social and political context in favor of a scrupulous attention to character development. Though this makes the battle piece almost cartoonish in its vain attempt to reconstruct the fast-paced decisions, accidents, and miracles of combat, Keegan still vindicates it. He argues that battle pieces are the best way of positioning historical analysis as closely as possible to the temporal and geographical site under discussion.

Keegan proceeds to analyze one critical battle from each of three important eras: medieval Europe, the era of Napoleon, and World War I. The particular battles he selects are unique in that they were waged on the exact same land. Keegan does this to stress that human arrangements, technology, and the experience of the soldier evolve through time and respond uniquely to geopolitical context.