Millis' book is largely a commentary on war as a social phenomenon in America. Its most useful aspect is its blending of military thinking with political theory, demonstrating, as well, war's relationship with society at large. He clearly shows that military policy is not formulated in a vacuum. Millis contributes much to the understanding of American history by arguing that matters of war complemented or even superseded politico-economic motives ever since the American Revolution. The fighting at Concord and Lexington had a significant impact on the creation of America. Beyond this, the Revolutionary War unleashed democratic forces--in politics as well as warfare--that its leaders did not intend and could not contain. Millis examines the unpredictability and uncontrollable nature of warfare, arguing that warfare itself has done much to create each "age" of American society.

Warfare matured along with society's political and social processes. The use of military force has long been a "social instrument" in America. Millis identifies several "revolutions" which shaped the public perception and practice of warfare. The democratic revolution in both warfare and politics, engendered by the American Revolution, created the concept of universal military obligation. An industrial revolution provided for technological modernization, along with better communication and transportation of forces. A managerial revolution allowed for quick mobilization of forces. The War Between the States is seen to be a time of transition militarily as well as politically. Plans for the actual use of force went relatively neglected between wars, and the Army existed largely as a "symbol" of power.

Throughout American history, the changing nature of warfare has largely determined policy. America long relied on the idea of voluntarism, mobilizing society only in times of crisis. World War I showed that voluntarism was insufficient to provide the necessary troops for twentieth-century warfare. The preparations in America during 1914-15 were to a significant extent mere political and social posturing; the necessary plans for action were largely neglected until America suddenly found herself drawn into the war. The trend this century of increasingly mechanized, large-scale warfare has sometimes served to push military actions, once engaged, beyond the bounds of political control. The World Wars and the nuclear age have given birth to "total warfare," which affects all aspects of society. For this reason, the nature of warfare has dramatically changed; no longer is it an effective "instrument of policy," Millis tells us. Even a defensive struggle in the nuclear age can invoke great forces of devastation. As a result, the settlement of disputes on the world stage can no longer be solved by going to war; warfare as a social institution no longer offers the solution to such problems. Millis concedes that he cannot foresee the future of world relations, but he calls on America to look to nonmilitary solutions and to avoid unleashing the uncontrollable "dogs of war." The central question that remains unanswered in this book concerns the proper military policy to be employed in peace time.