Texas was previously under the power of Mexico's dictator, Antonio Lopez de Santa Anna. the Texonians already wanted to be free from Mexico, but what sealed the deal was the settlers in America wanting to expand their land, leaving Texas with the hope of being accepted by America as one of their states. even though Andrew Jackson (Americas president at the time) didn't want to annex Texas because of the chances of firing up any more conflicts between Mexico and America, the people of the US urged Texas to become independent so that it COULD be annexed to the united states.