After the outbreak of World War I in 1914, the United States pursued a policy of non-intervention, avoiding conflict while trying to broker a peace. President Woodrow Wilson later argued that the war was so important that the US had to have a voice in the peace conference. The United States was never formally a member of the Allies but entered the war in 1917 as a self-styled "Associated Power". Initially the United States had a small army, but, after the passage of the Selective Service Act, it drafted 2.8 million men, and, by summer 1918, was sending 10,000 fresh soldiers to France every day. The war ended in 1919 with the Treaty of Versailles. The United States then adopted a policy of isolationism, having refused to endorse the 1919 Versailles Treaty or formally enter the League of Nations.