Doughboys: Slang term used to refer to American soldiers who served in World War I as part of the American Expeditionary Forces.
Trench Warfare: A type of combat where opposing armies dig trenches facing each other for protection and engage in battles from these fortified positions.
Armistice: An agreement between warring parties to temporarily stop fighting. The armistice signed on November 11, 1918, ended World War I.