▁part ▁of ▁a ▁prisoner ▁exchange ▁in ▁October ▁the ▁same ▁year , ▁Pr ent iss ▁was ▁promoted ▁to ▁major ▁general ▁and ▁served ▁on ▁the ▁court - mart ial ▁board ▁that ▁conv icted ▁Fitz ▁John ▁Por ter . ▁His ▁diss ent ing ▁voice ▁in ▁the ▁final ▁vote ▁dam aged ▁his ▁political ▁cl out . ▁Pr ent iss ▁was ▁sent ▁to ▁Ark ansas ▁and ▁won ▁the ▁Battle ▁of ▁Hel ena ▁on ▁July ▁ 4 , ▁ 1 8 6 3 . ▁In ▁ 1 8 6 3 , ▁he ▁res igned ▁to ▁tend ▁to ▁his ▁family . ▁Histor ian ▁Ez ra ▁J . ▁Warner ▁spec ulated ▁that ▁Pr ent iss ▁felt ▁that ▁he ▁was ▁being ▁sh el ved ▁after ▁having ▁proved ▁his ▁ab ilities ▁at ▁Sh il oh ▁and ▁Hel ena . ▁ ▁Post - C ivil ▁War ▁career ▁After ▁the ▁Civil ▁War , ▁Pr ent iss ▁became ▁a ▁lawyer . ▁He ▁was ▁later ▁appointed ▁as ▁post master ▁of ▁Beth any , ▁Missouri , ▁by ▁President ▁Benjamin ▁Harrison ▁and ▁was ▁re - app oint ed ▁by ▁President ▁William ▁McK in ley . ▁He ▁was ▁a ▁leader ▁in ▁the ▁Republican ▁Party ▁of ▁Missouri . ▁ ▁He ▁died ▁on ▁February ▁ 8 , ▁ 1 9 0 1 ▁in ▁Beth any ▁at ▁age ▁ 8 1 . ▁He ▁is ▁buried ▁there ▁in ▁Mi ri am ▁C emetery , ▁Harrison ▁County , ▁Missouri . ▁ ▁See ▁also ▁▁ ▁List ▁of ▁American ▁Civil ▁War ▁gener als ▁( Union ) ▁ ▁Notes ▁ ▁References ▁ ▁Daniel , ▁Larry ▁J . ▁Sh