Answer:
The battle that lasted for seven weeks at the end of WWI was the Meuse-Argonne Offensive.
Explanation:
The Meuse-Argonne Offensive was the final offensive of the First World War, being the largest operation and victory of the American Expeditionary Force (AEF) in that war. The offensive took place in the sector of Verdun, immediately north and northwest of the city of Verdun, between September 26 and November 11, 1918. It was developed as part of the offensive of Marshal Ferdinand Foch called Grand Offensive, which included attacks by the AEF and the Fourth French Army on September 26, the British Fourth Army on September 27, and other British and Belgian troops on Ypres on September 28. These operations allowed a general Allied advance over a large part of the Western Front, resulting in the defeat of the German Army and the signing of the November 11th armistice that put an end to hostilities between the Central Powers and the Allies.
