<P> As the conference 's decisions were enacted unilaterally , and largely on the whims of the Big Four , for its duration Paris was effectively the center of a world government , which deliberated over and implemented the sweeping changes to the political geography of Europe . Most famously , the Treaty of Versailles itself weakened Germany 's military and placed full blame for the war and costly reparations on Germany 's shoulders -- the humiliation and resentment in Germany is sometimes considered one of the causes of Nazi electoral successes and indirectly a cause of World War II . The League of Nations proved controversial in the United States as critics said it subverted the powers of Congress to declare war ; the U.S. Senate did not ratify any of the peace treaties and the U.S. never joined the League -- instead , the Harding administration of 1921 - 1923 concluded new treaties with Germany , Austria , and Hungary . Republican Germany was not invited to attend the conference at Versailles . Representatives of White Russia ( but not Communist Russia ) were present . Numerous other nations did send delegations in order to appeal for various unsuccessful additions to the treaties ; parties lobbied for causes ranging from independence for the countries of the South Caucasus to Japan 's unsuccessful demand for racial equality amongst the other Great Powers . </P>
regarding the treaty of versailles the u.s. senate decided in 1919 to
not ratify any of the peace treaties