Tuhia he tomokanga mo tenei whitianga - I te Pakanga o Mexico-Amerika, i whawhai ia i te Pakanga o Contreras me te Pakanga o Churubusco
, i te marama o Akuhata 1847. I a ia e mahi ana i Churubusco, i whara ano ia, ana ko tana mahi i reira i honoa ki ana mahi i Contreras i whakawhiwhia ki a ia te tohu ki te rangatira nui i te Akuhata 20. I uru a Walker ki te Pakanga o Molino del Rey i te timatanga o Hepetema ka whara ano ia, i tenei wa i muri. Mo ana mahi i reira, i whakawhiwhia ia ki a ia hei rangatira rangatira i te marama o Hepetema 8.