Native Texan Patriot. Born in San Antonio, Texas, in 1835, he supported the Texas Revolution against the Centralist opposition by leading a militia company to Monclova. After the battle of Gonzales in October 1835, Stephen F. Austin gave him a Captain's commission. He raised a company of men known as the Tejanos, which was involved in scouting and supply operations for the Texas Army. In December 1835, his group participated in the assault on General Perfecto de Cos's army at San Antonio. He entered the Alamo with the Texans when General Santa Anna's army arrived and was sent out by Lieutenant Colonel Travis as a defender to gain relief for the garrison. Upon reaching Gonzales he organized a company and was ordered by General Sam Houston to be his army’s rear guard. His company was the only Tejano unit to fight at the battle of San Jacinto. Seguín accepted the Mexican surrender of San Antonio on June 4, 1836 and at the rank of Colonel, served as the city's military commander through the fall of 1837. In command he directed burial services for the remains of the Alamo dead. He resigned his commission, was elected to the Texas Senate, he was the only Mexican Texan in the Senate of the republic, serving in the Second, Third, and Fourth Congress. He also served on the Committee of Claims and Accounts and as chairman of the Committee on Military Affairs. In the spring of 1840 he resigned his Senate seat, returned to San Antonio and became mayor. He became involved in growing hostilities between Anglos and Mexican Texans about conflicts on city property and his business interest with Mexico. He resigned as mayor on April 18, 1842 and left for Mexico with his family. While living in Mexico he formed a guard, serving as a frontier defense unit, protecting the Rio Grande and fighting Indians. During the Mexican War his company saw action against United States forces. At the end of the war he returned to Texas to ranch on land what is now Wilson County. In the 1850s, he was involved in local politics, served as Bexar County constable and an election-precinct chairman. In 1869, he served as Wilson County judge, later retired, moved to his son’s ranch in Nuevo Laredo, Mexico and remained there till his death. His remains were returned to Texas in 1974 and buried at Seguin, the town named in his honor, in ceremonies on July 4, 1976.