Ya yi yaƙi tare da rukunin a Fort Henry, Fort Donelson, Koranti, Shiloh, da Hatcher's Run. Daga nan sai ya kamu da cutar typhoid kuma an sallame shi a ranar 1 ga Agusta, 1862. Ya dawo bayan dawowa tare da Chicago Mercantile Independent Battery Light Artillery, inda ya yi yaƙi a Arkansas Post,
Port Gibson, Champion Hill, Babban Black River Bridge, Vicksburg, da kuma Mansfield. A Mansfield, an kama brigade kuma Arnold ya zama fursuna. An tsare shi a sansanin Ford a Texas na tsawon watanni goma sha huɗu.