After the Battle of Gonzales, the Texas army fought battles in other areas. They were successful, too. More Mexicans than Texans died in the early days of the war. Many volunteer Texans went home to their families. It seemed that Santa Anna would stay in Mexico rather than fight the Texans.
Except that he didn't. In early spring of 1836, he came north to crush the Texans. He held the Alamo siege, and battered the walls. This lasted for 12 days.