I am having trouble identifying the uniforms in the picture below. The man on the left is my grandfather. He was a Polish farmer from Suwalki, Poland. The story goes that he was conscripted by the Russians during the partition of Poland. He later fled to the United States and joined the US Army to fight in the Great War.
I don't recognize these uniforms as American at all. It would mean a lot to my family if anybody could help by pointing me in the right direction on how to identify this.