Final answer:
Juan Seguín joined Sam Houston and fought at the Battle of San Jacinto, a pivotal moment leading to the independence of Texas.
Step-by-step explanation:
Juan Seguín was sent as a messenger to warn Sam Houston about the situation at the Alamo. He would later join Houston and participate in the fight at the Battle of San Jacinto. This battle proved to be a decisive victory for the Texans. It was at San Jacinto, on April 21, 1836, where Sam Houston's army caught General Antonio López de Santa Anna and his troops by surprise during an afternoon nap, leading to Texas' independence.