Beginning in the early 1800s, Spanish military troops were stationed in the abandoned chapel of the former mission. Because it stood in a grove of cottonwood trees, the soldiers called their new fort “El Alamo” after the Spanish word for cottonwood and in honor of Alamo de Parras, their hometown in Mexico.
How the Alamo got its name By Kevin R. Young and Randell Tarin  It's difficult to pinpoint when the Valero mission was first called "Alamo." Many early references address La Compañía de Alamo de Parras as "El Alamo," which was often seen as an abbreviated name form in correspondence and other official documents.... http://www.sonsofdewittcolony.org/adp/history/mission_period/valero/valeroname.html
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