THE FIRST World War, the “Great War’’ that ended 93 years ago today, saw the United States emerge as a global power. But the war’s most lasting historical impact was its aftermath. Rather than use its battlefield success to win a critical peace in Europe, the United States turned inward. Massachusetts Senator Henry Cabot Lodge pushed the Senate to reject President Wilson’s League of Nations. An insular America chose isolation from the world and failed to lead when Hitler and Mussolini rose to power. The ultimate irony was that the “war to end all wars’’ led directly to an even more cataclysmic World War II two decades later.

This most urgent lesson of the Great War should give us pause as we arrive at another crossroads in our history with a clear choice to make about our role in the world. The 9/11 decade yielded a bitter and failed intervention in Iraq and stalemate in Afghanistan. After spending more than $1 trillion on the two wars alone, losing more than 6,200 young soldiers, and experiencing the trauma of recession since 2008, it is not surprising that voices of isolation are returning to our national debate. They can be heard on the extreme left of the Democratic Party and, especially, on the Tea Party-dominated Republican right.

Our internationalist president was right to declare in June that “it is time to focus on nation-building here at home’’ as rebuilding our economy and restoring national self-confidence are urgent necessities. And, while this new isolationism is not a full-blown call of retreat from the world, there is a palpable shift in attitude in Congress. It is an insidious turning inward by congressional budget leaders whose Draconian cuts will deny us the ability to lead globally at the very time when it is most critical for our economic health and political future.

How else can we understand the shifting winds in Washington? In its manic drive to slash bu