The disputed territory between the United States and Mexico during the Battle of the Alamo was Texas. At the time of the battle in 1836, Texas was considered a part of Mexico, which had gained independence from Spain in 1821. However, many settlers from the United States had migrated to Texas and desired independence from Mexico. This tension led to the Texas Revolution, which began in 1835 and culminated in the Battle of the Alamo in 1836. The battle was a significant event in the Texas Revolution, as it solidified the Texans' resolve to fight for independence and paved the way for their eventual victory in 1836.