Meuse-Argonne Offensive (5h 42min, sep 26, 1918 y – 13h 52min, nov 11, 1918 y)
Description:
 Many American soldiers involved in the battle, it was the last offensive of the war. It was one of the deadliest battle of the World War I. 
Added to timeline:
Date:
5h 42min, sep 26, 1918 y
13h 52min, nov 11, 1918 y
 ~ 1 months and 16 days