The United States was a formal participant in World War I from April 6, 1917 until the war's end on November 11, 1918. Before entering the war, the US had remained neutral, though the US had been an important supplier to Britain and other Allied powers. During the war, the US mobilized over 4,000,000 military personnel and suffered 110,000 deaths, including 43,000 due to the influenza pandemic.[1] The war saw a dramatic expansion of the US government in an effort to harness the war effort and a significant increase in the size of the US military. After a slow start in mobilizing the American economy and manpower, by spring 1918 the U.S. was poised to play a decisive role in the conflict. Under the leadership of President Woodrow Wilson the war represented the climax of the Progressive Movement as it claimed to bring reform and democracy to the world.