The Alamo is a myth that the Texicans were fighting for their freedom.
They were paid by the Slave interests to settle in Texas with the idea of having their plantations there. And the fact that Mexico was offering land cheap brought many as well but they had no interest in respecting the authority of the Mexican government.
They considered themselves superior to the Mexicans.
Then Mexico outlawed slavery so they set out to annex that territory by force so they could have the fertle land they needed.
Some how this story never is told in the movies.
And there were Mexicans fighting Sant Anna , but you never see them either.