Juan Morales, commander of Mexican forces in the battles of the Alamo and Coleto during the Texas Revolution, was born in Puebla, Puebla, Mexico, in 1802. He entered military service as a cadet in the Batallón de la Libertad in March 1821 and served in Agustín de Iturbide's army for the cause of independence from Spain. He became a supporter of the Plan of Casa Mata of February 1, 1823, along with Antonio López de Santa Anna, Vicente R. Guerrero, Guadalupe Victoria, and other dissatisfied revolutionaries, who forced Iturbide to abdicate the throne of Mexico. In December 1835, during the Texas Revolution, Morales was colonel of the Permanent Reserve Infantry Battalion of San Luis, the largest unit in Gen. Joaquín Ramírez y Sesma's Vanguard Brigade in Santa Anna's army for the Texas campaign. On March 6, 1836, at the battle of the Alamo, Santa Anna assigned Morales to lead about 100 men in the column of attack aimed at the south and main entrance of the mission compound. This was the palisade area defended by David Crockett's Tennesseans, thought to be the Alamo's weakest point. Although Texan artillery and sharpshooters forced Morales to move to the southwest corner, the Mexicans finally breached the palisade. Morales directed his men to seize the defenders' eighteen-pound cannon and turn it on the long barracks, then to attack the low barracks, where James Bowie was killed. Finally, Morales used the cannon to destroy the artillery platform atop the Alamo church, defended by James Butler Bonham and Almeron Dickinson.
After the fall of the Alamo, Santa Anna ordered Morales and picked units of the San Luis and Jiménez battalions to march from Bexar to La Bahía (Goliad) to reinforce Gen. José de Urrea in his campaign against Col. James W. Fannin, Jr. Morales's 500 veteran troops joined Urrea's forces on March 18 and contributed significantly to the defeat of Fannin's command in the battle of Coleto on March 19–20. With Urrea, Col. Mariano Salas, and Lt. Col. Juan José Holzinger, Morales negotiated surrender terms with the Texans on March 20, 1836. Afterward Urrea commanded Morales to bring the prisoners and captured munitions back to Goliad, then ordered the colonel and the Jiménez and San Luis battalions to join him as he proceeded to take the town of Guadalupe Victoria (now Victoria) en route to Brazoria. Morales then commanded Urrea's second brigade, composed of the San Luis and Tres Villas battalions, while Salas commanded the first, composed of the Jiménez and Querétaro battalions. After Santa Anna was defeated and captured in the battle of San Jacinto, Morales and Salas sustained Urrea's resentment against retreating across the Rio Grande, but followed Gen. Vicente Filisola's orders nonetheless.
In the Federalist Wars in northern Mexico and extreme southern Texas that followed Texas independence, Morales commanded a Centralist force of about 1,000 men, having achieved the rank of brigadier general in March 1839. He served in the Yucatán campaign under Santa Anna in 1842–43. Finally, as a major general, "the brave, active and popular" Morales was the commandant general of Veracruz in 1847 during the Mexican War. He refused to surrender the city to Maj. Gen. Winfield Scott, and when capitulation became inevitable he turned the command over to José Juan de Landero. Morales then left the city by boat the night of March 25–26, 1847, but not before inducing Gen. José Durán, commander of nearby Fort San Juan de Ulúa, to follow Landero's action and refrain from bombarding Veracruz once Scott's forces occupied the city. For these actions, Santa Anna ordered Morales, along with Durán and Landero, to be tried. Morales died in 1847 in Atlixco, Puebla.