The Alamo mission in San Antonio, Texas. Image online, courtesy Wikimedia Commons.
The obstinancy of Travis and his soldiers
was the cause of the death of the whole of them,
for not one would surrender.General Santa Anna
March 16, 1874 Letter
When Texas was still part of Mexico, a former Spanish mission known as "The Alamo" was captured by rebel forces. Those rebels were known as "Texians." Many had accepted the Mexican government’s offer of land and citizenship in the Texas territory.
Independence was in the air. America, to the north, had thrown off British rule in 1776. Mexico, long a Spanish possession, had declared its independence with the "Cry of Dolores," in 1810, and was free of Spain by 1824.
On March 2, 1836 - when about 200 Alamo defenders were nearing the fatal end of a siege personally led by Mexico’s new president (Antonio Lopez de Santa Anna) - Texians declared their independence from Mexico.
Some of the rebels were Americans who had become Mexican citizens. Others (from Ireland, Scotland, England and Wales, from France, Germany and other parts of the world) were recent arrivals to the Texas territory.
Why did they resist Santa Anna? What were they fighting for? How did they plan to form a new country (the Republic of Texas) a mere fifteen years after Stephen Austin (an American) received permission to colonize a portion of Mexico? And ... why did so few men aid the besieged Alamo garrison?
Answers to some of these questions remain shrouded in mystery. Answers to others depend on one's point of view.