Was the United States' entry into World War I a tragic mistake? Historians have debated this question for nearly a century. America entered the conflict with a burst of idealism that quickly turned into bitterness. President Woodrow Wilson's vision of making the world safe for democracy didn't turn out so well — or at least didn't seem worth the cost in blood and treasure to future generations. Historian Michael Kazin's War Against War: The American Fight for Peace 1914-1918 examines the mostly forgotten story of how a diverse bunch of activists, educators and politicians fought to keep the U.S. from joining the Allies against Imperial Germany. Mr. Kazin states his belief upfront that America should not have entered the conflict. That said, he presents the war as infinitely complex.