World War I 1914 1918. German fortified outpost in the Argonne forest. The Meuse Argonne Offensive, also known as the Maas-Argonne Offensive and the Battle of the Argonne Forest, was a part of the final Allied offensive of World War I that stretched along the entire Western Front. It was fought from September 26, 1918, until the Armistice on November 11, a total of 47 days. The battle was the largest in United States military history, involving 1.2 million American soldiers, and was one of a series of Allied attacks known as the Hundred Days Offensive, which brought the war to an end. The Meuse-Argonne was the principal engagement of the American Expeditionary Forces during the First World War.