Tuhia he tomokanga mo tenei whitianga - I tiimata a Jackson i tana mahi a te United States Army hei tuarua tuarua i te Kamupene K o te 1st U.S. Artillery Regiment, i haere ma Pennsylvania, i raro i nga awa o Ohio me Mississippi ki New Orleans, mai i reira ka eke nga hoia ki Point Isabel, Texas, ka tukuna ki te whawhai i te Pakanga Mexico-Amerika mai i te 1846 ki te 1848. I whakahaua te whakahau a Jackson ki te ripoata ki a General Taylor me te haere tonu ma Matamoros me Camargo ki Monterey ka haere ki Saltillo. I mua i te Pakanga o Buena Vista, i whakahaua te whakahau a Lieutenant Jackson kia wehe atu i te ope a General Taylor ka haere ki te waha o te Rio Grande, ka whakawhiti atu ki Veracruz. I mahi ia i te Siege o Veracruz
me nga pakanga o Contreras, Chapultepec, me Mexico City, i te mutunga ka whiwhi ia i nga whakatairanga e rua, me te taumata o te hoia tuatahi o te rangatira tuatahi. I Mexico a Thomas Jackson i tutaki tuatahi ai ki a Robert E. Lee.