Between April 1917 and November 1918, over two million Americans fought in the biggest and most costly war in European history to that date. Entering only at the tail end of four years of slaughter and horror, the United States helped turn the tide of the war in favor of the Allies, and brought America onto the international stage as a major military, financial and industrial power. Though at times unpopular at home, America's involvement in World War I was successful from a military standpoint. The largest national project the country had ever undertaken, World War I led to an increasingly large army and more power for the federal government. By the war's end, over 50,000 American soldiers lay dead on Flanders' Fields, with even more felled by disease. World War I marked the end of the old order in Europe. For the United States, it marked the beginning of the American Century.