Ya fara aikin soja nan da nan a cikin Yakin Mexico-Amurka. A lokacin wannan yakin, an ba shi izinin zama kyaftin don aikinsa a yakin Contreras da
Churubusco kuma an daukaka shi zuwa na farko Lieutenant kwanaki shida daga baya. Bayan ya koma Amurka bayan yakin, ya zama mataimakin farfesa na zane a West Point daga 1850 zuwa 1853 kuma ya yi yaƙi da Seminoles a Florida daga 1856 zuwa 1858. An daukaka shi zuwa kyaftin a ranar 22 ga Nuwamba, 1860.