Final answer:
Texas settlers wanted to overthrow Santa Anna to restore the power of the Mexican states and maintain their own social systems, such as slavery, which had been facilitated by America's colonization and expansion westward. Santa Anna's centralization of power under the Siete Leyes, which took away Texan political voice, spurred the Texas Revolution, leading to the declaration of the Lone Star Republic.
Step-by-step explanation:
The Texas settlers wanted to overthrow Santa Anna to help restore the power of the Mexican states. General Antonio López de Santa Anna gained popularity as a military hero but ultimately became a centralist president who overturned the Mexican Constitution of 1824 in favor of the Siete Leyes, which centralized government power and dissolved Congress.
This act was intolerable for the Texans, who were used to separation of powers and having a political voice. In response, they formed the Federal Army of Texas to defend the Constitution of 1824 against Santa Anna and the centralists. The ultimate goal was to secure their independence and maintain their own political and social systems, including the practice of slavery, which had been outlawed by Mexico in 1829.
The annexation of Texas to the United States was a separate yet related issue. It was supported by many in Texas and the U.S. as a way to expand west and incorporate the lands into the U.S. Still, the annexation was fraught with controversy, including the potential to reignite political tensions over slavery and the balance of power between free and slave states.