a man who was very important in mexico in the early 19th century was antonio lópez de santa anna. he was the president of mexico 11 times. when he became a dictator, texas declared independence (1836). the battle of the alamo was part of this texas revolution. between 1846 and 1848 there was war between mexico and the united states. in this war mexico lost its large northern areas, which became the southwestern united states. after this war santa anna was sent away to venezuela.