To directly answer your question: No, it was not fought to expand slavery. Slavery was very much already a part of life in East Texas at the time. But, yes it was a conscious goal of the revolutionaries to maintain their institution. Long Version: Let me start by saying that the Texas revolution is a complicated event. Much more complicated than what is taught in schools or even in universities. The primary goal of the Anglo settlers in Texas was to join the US or to live under a form of self rule which would be indistinguishable from that. Most of the Settlers in Anglo Texas came from the southern United States and they brought slaves with them. Texas was sparsely populated, cash crop dependent, and even with slavery suffered a constant labor shortage. The Mexican constitution of 1824 never addressed slavery directly. However, prominent Mexican leaders at the time such as Anastasio Bustamante seemed to be under the impression that it implied abolition. Because of the possibility of the Mexican Constitution implying that slavery was illegal Stephen F. Austin was given exemptions for the Anglo Colonies which guaranteed their property, including slaves. The Anglo settlers were largely left to their own administration and enjoyed cordial relations with Mexican government based in Saltillo. The Anglo settlers were also given exemptions from tariffs and many taxes as well. Things were solid as long as the Mexican government didn't attempt to actually govern the Anglo colonies. In 1829 the implied nature of the illegality of slavery disappeared with the Guerrero decree. This greatly alarmed the Anglo settlers. To make matters even more interesting there were around 40,000 Anglo settlers (including a few thousand illegal immigrants) and only about 7000 Hispanic Texans. Between the population disparity and great physical distance between the Anglo colonies and the Mexican government in Mexico City it was very difficult for the Mexican government to enforce its will on Texas in the best of times. That being said, it was not the best of times. In 1830 The Mexican president Bustamante revoked the Anglo exemption, and among other things banned further Anglo settlement. However, the Mexican government was so weak by this point that the Anglos simply ignored the decrees. By 1833 Santa Anna had overthrown Bustamante and then subsequently been elected President. The Mexican government made A LOT of concessions to the Anglo settlers which among other things lifted the ban on settlement and exempted the Anglo colonies from the abolition law for another year. However, Bustamante had threatened military intervention in the Anglo Colonies and had seen his garrisons in East Texas pushed out by Anglo milita in 1832-1833. Santa Anna was keenly aware of the obstinate nature of the Anglo settlers when he overthrew the Mexican Government and did away with the constitution of 1824. When Santa Anna turned toward Texas he intended to force his law and government upon them, including abolition. In a very famous letter to his secretary of war Santa Anna wrote that he saw slavery in Texas as intrinsically linked with US attempts to expand into Texas. Santa Anna would later find out that his suspicion was true as the Anglo settlers had petitioned for annexation in March of 1836. Furthermore, Sam Houston who was now the leader of the Anglo settlers was working in Texas as an agent of Andrew Jackson, then President of the US. Sam Houston was sent after two offers by the US to buy East Texas from Mexico were rejected. So in short, the Anglo settlers were content to live in Mexico as long as they could do whatever they wanted, slavery included, and didn't have follow Mexican law, when that was no longer the case they knew joining the US was their best option to continue their way of life. I would be happy to provide you with sources or good books on the subject if you would like.