If the war was initially fought between Great Britain and Germany, why did the United States give Germany the Peace Treaty?

If the war was initially fought between Great Britain and Germany, why did the United States give Germany the Peace Treaty? Why would Woodrow Wilson take the important part of pushing Germany to pay for the damages of the war? Do you think some of this has to do with Conrad? Think of the beginning of the war to the end. If Conrad wouldn't have pushed the issue of war, in the beginning, would we still have seen the first of many wars?