American participation in the First World War developed slowly throughout 1917 to a mighty torrent during the last six months of the war. United States participation undoubtedly helped not only repel but to stop all German assaults on the Western Front: it had substantially aided in defeating Imperial Germany. Through primary and secondary sources a timeline, as well as a few of the more significant events, has been established following the United States' involvement in the war. Special attention has been focused on the United States Third Infantry Division and its part in the July 15- 17, 1918 Second Battle of the Marne. The Third Infantry Division would see the war throughout its remaining battles and aid in the occupation of Germany. However, it is most famous for the Marne battle.