The correct answer is "A large Mexican army attacked a small force of Texans."
The Battle of the Alamo was initiated with the attack of Mexican troops led by President Antonio Lopez de Santa Anna on the Texan fortress of The Alamos on February 23, 1836. The Texan and American settlers who lived there were killed during the attack. As a response, the Texan Army allied with American Settlers defeated the invading Mexican forces on the Battle of San Jacinto on April 21, 1836.