For those of you interested in reading about American units that participated in battle in WW1, see the link.
My Grandfather, William John Greenfield, 1895-1968, was a Corporal and member of Company C, 18th Machine Gun Battalion. I never really knew my Grandfather, as I was only 6 when he passed away. He's buried in Long Island National Cemetery. The only thing I know about his service is what I found in the link I provided:
6th Division
12th Infantry Brigade:
54th Infantry—
18th Machine Gun Battalion
(1) Gerardmer sector, Vosges, France, 3 September-12 October, 1918.
(2) Meuse-Argonne offensive, France, 1 November-ll November, 1918.