The war started because Mexico started to let Americans to farm and live in Texas. So Americans started to bring slaves to do all the work, Mexicans didn't like that Americans brought slave to Texas because Mexico doesn't like to own slaves.
When the war started the American locked them selves in a house so for 3 days so when Mexico shot at the house. Then Mexico wen't in side of the house, when Mexico came out of the house they were surrounded.