The significance of his attendance can be summed up in two major points.
He was the first American President in attending a Peace Conference, and not only he attended but he was one of the major powers who actively participated in it by proposing peaceful negotiations to a long-lasting peace in Europe, that included not to punish Germany harshly.
He also proposed the draft of Covenant of League of Nations, which laid the groundwork for the formation of the League of Nations. This was an international cooperation that aimed to resolve international disputes and prevent another world war ever from happening that included conditions for all countries involved (Disarmament, free trade, freedom of the seas, open diplomacy, etc). Although the U.S. Congress refused to be part of the League, the organization was eventually created and worked for several years.
