See quotations.
1846. The offer was quickly accepted—for the dog-soldier was poor. (Note.) This is the title of those selected to superintend the civil affairs of [an Indian] village.—Rufus B. Sage, ‘Scenes in the Rocky Mountains,’ p. 94 (Phila.).
1878. These [“dog soldiers”] are outcasts or runaways from all the [Indian] tribes, who get together in squads of from five to five hundred.—J. H. Beadle, ‘Western Wilds,’ p. 562.
