You think that's bad. I've heard lefty whackos claim that the Founding Fathers only wanted independence because the King was about to outlaw slavery in the colonies.
While it can't be said that the Alamo was fought directly for slavery, Mexico's abolishment of slavery in 1829 is what led Texas to revolt. Texans specifically requested to be exempted from abolition and when Mexico refused they revolted.
Texas joined the United States as a slave state and was the 7th state to secede during the Civil War. It is the only state to have revolted TWICE over slavery.
Truth hurts, but it's better than the alternative.