Answer:
The annexation of Texas.
Explanation:
The annexation of Texas in 1845 outraged the Mexican public and the government. Â After the US government and Texas concluded a treaty of annexation, Mexico severed relations with Washington. Though there was not war immediately as Mexican authorities had threatened, tensions remained high because of disputes over Texan borders. Â The big conflict started in 1846, and though the US army was superior in weaponry and technology, Mexicans put a stiff resistance.
