Answer:
Fearing that his small group of men could not withstand an assault, Travis wrote a letter seeking reinforcements and supplies from supporters. The letter closes with Travis's vow of "Victory or Death!".
So they would not be tempted to sin
They had a very good army, and also had funds to recruit more soilders even foreign soilders.
Mexico's economy is the 15th largest in the world in nominal terms. Hope this helps :)