From the Annals of the Abolitionists –  In 1829, Mexican President Vicente R. Guerrero issued the Guerrero Decree which abolished slavery throughout the Republic of Mexico except the Isthmus of Tehuantepec.  This was a major spark for the Texas Revolution as many Anglo settlers had brought slaves with them and were opposed to abolition.  The role of the preservation of slavery as a cause of the revolution has been understated in Texas history for as long as Red can remember. It was far from the only cause, but there were approximately 5000 enslaved persons out of a total of about 38,000 people (not including Native Americans) living in Texas at the time of the revolution.  After winning independence, the Constitution of the Republic of Texas of 1836 provided:

All persons of color who were slaves for life previous to their emigration to Texas, and who are now held in bondage, shall remain in the like state of servitude…  Congress shall pass no laws to prohibit emigrants from bringing their slaves into the republic with them, and holding them by the same tenure by which such slaves were held in the United States; nor shall congress have the power to emancipate slaves; nor shall any slave holder be allowed to emancipate his or her slave without the consent of congress, unless he or she shall send his or her slave or slaves without the limits of the republic.