Seneca Series — a series by Zanski

Ohio farm boy Judah Becker, part Seneca by his grandmother, and trained in the old ways by his full-blood uncle, joins the Union Army at Chattanooga in 1864 just after turning 18. He becomes a scout-sharpshooter, a role that will carry him from Georgia and Tennessee to Louisiana, Texas, and finally, New Mexico, in the 1880s. There are improvised maps at https://senecaseries-zanski.blogspot.com/