The 1919 peace settlement was not perfect, but for war-shattered Europe it was an acceptable beginning. The remaining problems could be worked out in the future. Moreover, Allied leaders wanted a quick settlement for another reason: they detested Lenin and feared his Bolshevik Revolution might spread.

It came as a major shock, therefore, when the United States quickly reverted to its prewar preferences for isolationism and the U.S. Senate rejected the Versailles treaty. Republican senators led by Henry Cabot Lodge believed the treaty gave away Congress’s constitutional right to declare war. In failing health, Wilson rejected all attempts at compromise. His obstinacy ensured the treaty would never be ratified in any form and that the United States would never join the League of Nations. Moreover, the Senate refused to ratify Wilson’s defensive alliance with France and Great Britain. Using U.S. action as an excuse, Great Britain also refused to ratify its defensive alliance with France. Betrayed by its allies, France stood alone, and the great hopes of early 1919 had turned to ashes by year’s end.