After Mexico declared their independence from Napoleon and Spain in 1821, they start allowing American settlers on their land. These US settlers still kept their customs, but they improved the Mexican economy
The Revolt in Texas
Moses Austin had first gotten the permission to allow Americans to settle in Texas. He died a year later, so his son, Stephen Austin was the one to bring the Original 300 families into Texas
Sam Houston and the Revolution
The Mexicans started to feel threatened by the abundance of American settlers, so they outlawed slavery and enforced it, and enforced the rules of learning the Spanish language and conversion to catholicism. They also wanted the Americans to become Mexican citizens.
Defeat at the Battle of the Alamo
After the Americans started to take over Texas, The Mexican government stopped immigration. They also made Americans pay taxes. This angered many and they started a revolt which got shut down by the army.
You are not welcome anymore
Sam Houston led a revolution against Santa Anna's army. They then wrote the Texas Declaration of Independence, and had Sam Houston and the Texian leaders sign it.
In March of 1836 was the Battle of the Alamo. 150 people retreated to an old mission and held off an army of 6000 for 12 days. Virtually everyone there was killed however, and it became a military defeat for Texas. The famous battle cry was, "Remember the Alamo!"