[3][Note 1] He was commissioned a captain by Stephen F. Austin in October 1835[4] and was tasked with supplying the Texian troops with food and provisions.

[5] Seguín sent out scouting parties to the Missions of San Antonio in search of a suitable base camp for the Texians [6] and participated in the early successful Battle of Concepcion.

[8] Upwards of 160 rancheros (Mexican ranch owners) and other Tejanos under Seguín, José Carbajal, Plácido Benavides, Salvador Flores and Manuel Leal joined Austin and approximately 400 Texians at the Siege of Béxar.

[16] After the Alamo, he re-formed cavalry companies at Gonzales and acted as the rear guard, providing protection for fleeing Texas families during the Runaway Scrape.

[21] Texas army Brigadier General Felix Huston ordered Seguín in early 1837 to arrange for burial of the Alamo defenders' remains that had been left where they were burned.

An account provided by Seguin, in the March 28, 1837 issue of the Telegraph and Texas Register, states they were buried where the majority of ashes had been found, but was not specific about the location.

Twenty-eight years later in correspondence with Hamilton P. Bee, Seguín remembered placing the remains in a tomb inside the "Cathedral of San Antonio".

In 1839, Seguín, captain of a Texas force of about fifty-four men, again protected the colonists in the Henry Karnes campaign against the hostile Comanche Indians.

[29] A counterattack was planned, and even though Seguín pursued the army of Ráfael Vásquez, chasing them from Texas,[30] he was deemed to be to blame for the attack.

He fled to Mexico to "seek refuge amongst my enemies", where he was captured, arrested and coerced to enlist in the Mexican army as a staff officer.

He returned to San Antonio with the opposition army of Adrian Woll[32] in September 1842 and later served under Santa Anna in the Mexican–American War of 1846–1848.

By the year's end, he had returned,[33] building a home[34] in 1852; adjacent to his father Erasmo Seguín's house, and ranching in Floresville, Texas.

His remains were returned to Texas in 1974 and as part of the nation's Bicentennial celebration were reinterred in his namesake town, Seguin,[36] during ceremonies on July 4, 1976.

A large monument, depicting him on horseback waving his saber, now honors his service to Texas, in the downtown Seguin Central Park.