Sam Houston was opposed to slavery. Texas had 10,000 slaves when Santa Anna overthrew the Republic of Mexico, declared himself Emperor, and six states seceded including Texas. But Texas won.
Also, that was about twenty years after the Mexican slave genocide, when Mexico went from 10% black to 1% today in one year. Mexicans never gave a damn about slavery. Mexico ended public school segregation in 1996. In 2020, you can finally identify as African-Mexican on a census form.
Mexico imported more slaves per capita (200,000) than America (400,000) and then genocide'd them.
It stole Texas from France, California from Russia, =nd southern Mexico from Guatemala.
* I forgot burned and looted.