Explain Wilson's last battle, why was this a great defeat to him?

Wilson's proposal called for the victorious Allies to set unselfish peace terms with the vanquished Central Powers of World War I, including freedom of the seas, the restoration of territories conquered during the war and the right to national self-determination in such contentious regions as the Balkans.

The devastation and carnage of the First World War grimly illustrated to Wilson the unavoidable relationship between international stability and American national security