The problem was that Houston's troops took orders about as well as a herd of cats at a laser disco. They were notorious for ignoring the orders of Houston's predecessor, and Houston himself had just as much luck. They listened to him right up until he got to the word "retreat," and everything else out of his mouth sounded to them like "blah blah blah I'm a big weenie coward who doesn't love America." Instead of following Houston's orders to evacuate, the rebels fortified the Alamo and holed themselves up inside. When Houston sent Colonel Jim Bowie back to convince the army to leave, Bowie took one look at the shitty fort, wiped away a patriotic tear, and joined them instead. Houston thought, "Sure, whatever, fuck it," and left them to their fate.
George Eastman House
"Fine, stay. We'll see who ends with 'Metropolis Namesake' on their resume, dipshit."
The rebels put up an impressive fight, but probably not as impressive as Hollywood and the Texas school curriculum would have you believe. Far from going down in a hail of gunfire atop a pile of dead Mexicans, Jim Bowie was killed while lying sick in bed, and there's no record of what happened to Davy Crockett. And although the Alamo is considered a shrine to freedom today, right after the war it was seen as a kind of embarrassing footnote that they tried to sweep under the rug.