Enthusiasm in the camp was fueled now by daily dispatches of Americans in action at last. Through most of that spring, while Captain Truman was at Montigny-sur-Aube, the numerical superiority of the Germans on the Western Front had become clear. The great question was whether American forces would arrive in time and in sufficient strength to make the difference. By June the Germans were back again on the banks of the Marne, within cannon shot of Paris. The situation was grim. The leaders of France, Italy, and Great Britain warned Woodrow Wilson of the “great danger of the war being lost” unless American forces became available as rapidly as possible. Pershing had been bound and determined to commit his troops only as a separate American command, but because of the emergency more than 250,000 Americans were rushed to the front to support the French under the command of Marshal Ferdinand Foch. The Americans fought bravely at Château-Thierry and Belleau Wood. Then, on July 15, the Germans unleashed another huge offensive aimed at Paris, the Second Battle of the Marne, sending fifty-two divisions against thirty-four Allied divisions, nine of which were American. In three days, from July 15 to July 18, the tide of battle turned. To Ludendorff, American forces had been the “decisive” factor, and the German chancellor later confessed that “at the beginning of July 1918, I was convinced . . . that before the first of September our adversaries would send us peace proposals. . . . That was on the 15th. On the 18th even the most optimistic among us knew that all was lost. The history of the world was played out in three days.”

(http://www.autoadmit.com/thread.php?thread_id=5893463&forum_id=2/en-en#50070131)