To understand what we are doing in Iraq, we have to go back to a war that is almost a hundred years old. In its day it was called The Great War. Now we call it World War I. No matter what we call it, this war forever changed America's relations with the rest of the world.

President George W. Bush has been castigated by some critics for failing to work with the United Nations in the war with Iraq. World War I was the first act of the ongoing drama of the United States' involvement with the world in the role of a great power. When Woodrow Wilson returned from the Paris Peace Conference and asked the Senate to ratify his decision to join the League of Nations, Americans began arguing about how we should relate to an international organization, whose noble goal was, among other things, to keep the peace. Wilson claimed that if we failed to follow his leadership, we would "break the heart of the world."

Wilson thought America should surrender a significant amount of her sovereignty to the League of Nations, which he considered his personal invention. He had largely written the "covenant" or charter himself. When he sought the Senate's approval, many senators, both liberals and conservatives, strongly disagreed. They insisted on reservations that would protect the Monroe Doctrine and America's right to decide for itself whether to wage war. Senator Henry Cabot Lodge, the head of the Foreign Relations Committee, urged the Senate and the American people to decide this question only after "sober second thought."

Lodge's argument prevailed. The Senate rejected Wilson's version of the League. In spite of pleas from cabinet members and leaders of his own party, the president refused to compromise. A second vote also failed but the grimly determined Wilson turned the 1920 presidential election into a "great and solemn referendum" on his version of the League. The Democrats lost in a stupendous landslide. The American people rejected Wilson's league. When Franklin D. Roosevelt and his successor, Harry S. Truman, created the United Nations after World War II, they did their utmost to avoid Wilson's mistakes. Delegates to the UN were called ambassadors, stressing that the countries who sent them retained their sovereignty. Truman used his friendships with key senators to win overwhelming approval of the UN charter.

The politics of the Cold War soon disillusioned Americans with the UN as a body capable of arbitrating international disputes and avoiding war. The Communist empire relentlessly manipulated the UN's structure to its advantage. Within two years of its creation, Truman's joint chiefs of staff and his Secretary of State, General George C. Marshall, were telling him that "the ability of the United Nations...to protect, now, or hereafter, the security of the United States" was virtually nil. Henceforth, American presidents worked with the UN when possible but never allowed it to dictate American foreign policy.

What should we make of this unfinished drama? Historian Lloyd Gardner may have the best answer. He argues that when America intervened in World War I, it made a covenant with power. Painfully, with mistakes aplenty, the United States discovered power is at the heart of history. Because it was the strongest most prosperous nation on the globe, how it used its power was bound to have a large impact on the rest of the world.

At the Paris Peace Conference, Wilson and the United States discovered there were limitations to America's power. Other powerful nations simply refused to yield to Wilson's idealistic "fourteen points" (principles) for preserving peace. French premier Georges Clemenceau sneered that God had been satisfied with ten commandments. Additional limitations on America's power in 1918 resided in the tormented, hate-filled minds and hearts of the war-ravaged people of Europe, perhaps even in that universal idea of human nature itself. Still more limitations lay in the illusions of idealism -- Wilson's tendency to believe that noble slogans can be easily translated into meaningful realities.

Throughout the twentieth century, the United States' relations with the rest of the world have veered between idealism and an often harsh realism. In World War II we demanded unconditional surrender from Germany and Japan and endorsed the mass bombing of civilians in Germany and the use of atomic weapons in Japan to get it. Then we spent billions to revive these nations as prosperous democracies. Exactly how this great dichotomy between idealism and realism should be handled will always be debatable.

This is the lens through which we should view President George W. Bush's war with Iraq and its aftermath -- a lens painfully forged by the decisions of previous presidents. Because some presidents -- Wilson, Lyndon Johnson in Vietnam -- failed to make the covenant work does not mean it is unworkable. It takes time and a readiness to mingle tough realism with idealism -- but the free societies of South Korea and the Philippines, and the democracies of Germany and Japan are proof that America's covenant with power can become a creative force for a peaceful world.