President Wilson proposed that the Allies create a League of Nations to forever stop another War from happening.  The other Allies were unimpressed by the idea, far more concerned with making certain their enemies would never again be a threat.  They called for ruinous reparations payments from the defeated foes, and Wilson agreed to allow them as long as the Allies joined his League.  And thus the League of Nations was born from the ashes of War and total victory.