I know nothing about these soldiers but I think they are union? Very cool photo with flag in background.
The item "1/4 Plate Tintype Civil War Soldiers. Civil War Union" is in sale since Tuesday, January 09, 2018. This item is in the category "Collectibles\Photographic Images\Vintage & Antique (Pre-1940)\Tintypes". The seller is "bryan676869" and is located in Two Harbors, Minnesota. This item can be shipped to United States.