Antonio López de Santa Anna, Caudillo of Mexico at many times over many years, personally lead troops into battle against the Texas Revolutionaries and personally ordered the slaughter of remaining forces after the Alamo was overtaken. For this he was widely feared and loathed by the Texan's who heard about the massacre, until the
Battle of San Jacinto. There his forces were decimated in the infamous 19 minute battle, Sam Houston's army reversing their retreat and attacking the drunk and sleeping Mexican Army. Santa Anna was caught shortly thereafter, humiliated and stripped of power in the eyes of Texans, Americans, and even his homeland Mexicans. He was only kept alive due to Houston's long term planning, figuring that having Santa Anna alive would make them look merciful, compared to Santa Anna's brutal butchery, and useful as a negotiation tool. But many of Houston's men still despised Santa Anna, and many wanted to hang him for the
Goliad massacre despite Houston's direct orders.
Let's say Houston's men disregard their Commander-in-Chief and kill Santa Anna themselves, hanging or just shooting him when given the chance, what are the long and short term effects? Obviously Texas is still going to be claimed by Mexico, but will they wait more or less if Santa Anna is dead. What would happen in Mexico with their on-again off-again dictator dead for good? How would the Mexican-American War go without the leadership of Santa Anna?