Even though white US settlers had taken an oath to obey Mexico's constitution and laws to get the land they settled on, as soon as Mexico made it clear they intended to enforce the law, even in Texas, slaveowners started talking revolution and annexation to the US.
When I was going to a community college in Texas, I brought this up with one of my professors as part of why I wasn't particularly impressed by the grand revolutionary history of the state.
He was... rather upset about my comments, and insisted it Wasn't Like That, Really.
So when you hear these present-day secessionists talking about an independent Texas, know that they're evolving a "glorious legacy" of a fifth-column movement of proslavery landgrabbers and oathbreakers, one that had disastrous consequences for both Blacks and Natives in the long run.