By the beginning of the 20th century, the United States had already become an international power and a recognized force at sea, but its army remained little more than a frontier constabulary. In fact, when America finally entered World War I, the US Army was still only a tenth the size of the smallest of the major European forces. While most previous work on America's participation in the Great War has focused on alliance with Great Britain, Robert Bruce argues that the impact of the Franco-American relationship was of far greater significance. He makes the case that the French, rather than the British, were the main military partner of the United States in its brief but decisive participation in the war - and that France deserves much credit for America's emergence as a world military power.