One hundred years ago on April 6, the United States declared war on Germany and entered World War I. It was an event that changed America, and the world, forever.

America’s entry into that war was the result of the dream of one man, President Woodrow Wilson. In the light of America’s experiences in Vietnam, Iraq, and Afghanistan, it’s easy to retrospectively dismiss our participation in World War I as the first egregious exercise in Wilsonianism — an act of high-minded liberal idealism and moralism leading to disaster rather than redemption.

Yet seeing this centennial exclusively through that lens is a mistake. Whatever else it was, America’s role in what was then the world’s bloodiest and most destructive war signaled the emergence of the U.S. as the arbiter of a new world order, one that would be built around America’s economic strength, military power, and moral authority as promoter and defender of democracy and freedom. Assuming that role and burden has caused the U.S. a good deal of trouble and brought considerable cost, much of it in human lives — but far less cost, one has to argue, than if the U.S. had stayed out of World War I and evaded a responsibility we still carry today, however reluctantly: that of the superpower of freedom. 

... The conventional view is that it is the end of World War II that marked the creation of a U.S.-centered world order. In fact, it was World War I — starting with the economic and financial might the U.S. acquired during the war as Wall Street replaced London as the center of world finance, and growing as U.S. economic power was deployed to feed and then rebuild a shattered post-war Europe, including Germany and even Soviet Russia.

This shift in world power began even before America formally entered the conflict. On April 1, the day beforeWilson’s speech to Congress, the U.S. government extended an unprecedented $250 million in credit to Great Britain, with another $3 billion awaiting congressional approval. Overnight, Britain and the other allies became completely dependent on the U.S. to underwrite their purchases of war matériel — a debt that continued to mount until, by war’s end, the world owed the U.S. in excess of $10 billion, with Britain alone owing more than $4 billion and France upward of $3.4 billion. (To get a sense of the size of the debt in today’s money, add three or four zeroes.)

One could say that on April 1, 1917 — April Fool’s Day — the United States became the most powerful nation on earth, and that entry into the world war was merely anticlimax. Of course, some argue that Wilson should have used America’s financial leverage to force the Allies to the peace table without entering the war directly — but that would have left Imperial Germany as the dominant power in Eastern as well as Western Europe. A better criticism is that he should have entered the war earlier, in 1915 or 1916, before the Western democracies had exhausted themselves and before Russia had been shattered by revolution.

In any case, the armistice in November 1918 put the final seal on the United States’s status as the world’s lone superpower, which no future president could afford to ignore or deny. ...