The Library of Congress's Flickr collection includes 700+ high-res scans of ambrotype and tintype photos of US Civil War soldiers. "These fascinating photographs represent the impact of the war, which involved many young enlisted men and the deaths of more than 600,000 soldiers. The photos feature details that enhance their interest, including horses, drums, muskets, rifles, revolvers, hats and caps, canteens, and a guitar. Among the rarest images are African Americans in uniform, sailors, a Lincoln campaign button, and portraits with families, women, and girls and boys."
Visit Civil War Faces.