Ka cika wannan magana: Yanayi ya ci gaba da taɓarɓarewa a gefen Rio Grande. Amurka ta yi ikirarin Rio Grande a matsayin iyakar kasa da kasa yayin da Gwamnatin Mexico ta yi ikirarin Nueces ita ce iyakar da ta dace. A farkon shekara ta 1846, Janar Zachary Taylor ya gina sansani a kan Kogin Rio Grande da ke gaban garin Matamoros na Mexico. A watan Afrilu, 'yan Mexico sun mayar da martani ta hanyar aikawa da rundunar sojan doki kimanin 1600 a fadin Rio Grande inda, a ranar 25 ga Afrilu, suka mamaye rundunar sojojin 60 a karkashin Kyaftin din Amurka S. B. Thornton. Sojojin Mexico a Matamoros sun ci gaba da karuwa a watan Afrilu. A ƙarshen watan, Janar Taylor ya damu game da hanyoyin sadarwa tare da babban sansaninsa a Point Isabel, kusa da bakin Rio Grande. Saboda haka, a ranar 1 ga watan Mayu, Taylor ya koma mafi yawan sojojinsa zuwa Point Isabel, ya bar wani karamin rukuni na bindigogi da bindigogi a karkashin Maj. Jacob Brown a sansanin da ke gaban Matamoros. Ba da daɗewa ba Mexicans suka sanya wannan sansanin soja (daga baya aka kira Fort Brown) a ƙarƙashin mummunan hari. Ranar 7 ga watan Mayu, Taylor ya tafi wurin ceto tare da kimanin mutane 2,300. A safiyar ranar 8 ga Mayu, lokacin da kadan ya wuce rabin hanya zuwa sansanin soja, 'yan Amurkan sun fuskanci fuska da fuska tare da abokan gaba, wani karfi mai yawan mutane 6,000, wanda Janar Mariano Arista ya umurce shi. Its dama flank huta a kan wani tsawo da aka sani da
Palo Alto (bayan da aka yi alkawarin alkawari). Taylor ya motsa ba tare da jinkirin shiga cikin yakin ba, ta yin amfani da bindigarsa don rufewa da kafa sojojin. An ci gaba da shiga har sai da dare, lokacin da Mexicans suka janye. Amfani da wutar bindiga mai tasiri ya kasance babban alhakin nasarar Amurka. Asarar Amurkawa sun kasance 9 da aka kashe da 47 da suka ji rauni. 'Yan Mexico sun sha wahala fiye da 700, ciki har da kimanin 320 da suka mutu.