Arminius's armor consisted of wrought iron backed with teak plating. The conning tower was protected by 114 mm (4.5 in) of wrought iron on 229 mm (9.0 in) of teak. The armored belt ranged in thickness from 76 mm (3.0 in) of iron on the bow and stern to 114 mm amidships, the entire length of which was backed by 229 mm of teak.