This book provides a reasonably complete account of events in the United States during the nineteen months of American belligerency in the First World War, but it also seeks to do more than that. I have used the occasion of the war as a window through which to view early twentieth-century American society. From that vantage point, I believe, some familiar historical landscape can be seen in a new light, and perhaps some new terrain identified. The book, therefore, is not a comprehensive chronicle of all that happened in wartime America, though the pages that follow contain much of that sort of detail. Neither is it, strictly speaking, a study of the impact of the war on American society, though dimensions of that impact are frequently examined. The book might best be described as a discussion of those aspects of the American experience in the First World War that I take to be crucial for an understanding of modern American history.
The paramount theme of any account of American participation in the Great War of 1914-18 must be the historic departure of the United States from isolation and all that isolation implied. That departure not only spelled the abandonment of nearly a century and a half of American diplomatic practice, a commonplace observation to which I offer neither dissent nor elaboration. It also compelled the United States, as almost never before, to measure itself against Europe, even to compete with Europe for a definition of the war's meaning and for the fruits of