Seguín was commissioned as a captain in the regular Texas army. Upon the return of Santa Anna's army, Seguín joined William B. Travis on February 23, in the Battle of the Alamo. Although serving at the Alamo during the thirteen-day siege, he did not actually participate in the final battle of the Alamo. He was chosen to carry the Alamo message through enemy lines, that the Texans "shall never surrender or retreat." Seguín got that message through to the other soldiers on the Texian side. He then returned with men to reinforce the Alamo, but it had already fallen to Santa Anna's army. 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. His company, with Captain Moseley Baker's company, blocked the Mexican army from crossing the Brazos River, preventing them from overtaking the Texians. His cavalry command, participating as infantry with Sherman's company, fought in the victorious Battle of San Jacinto. In May 1836, he was promoted to lieutenant colonel. On June 4, as a representative of the Republic of Texas, he accepted the formal surrender of the Mexican forces in the Alamo. Life under the Republic of Texas After Texas became a Republic, he was the head of the San Antonio military, commanding a force to defend the western frontier. 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. Ashes were identified and collected at three unrecorded sites. Prior to the February 25 funeral, the casket lay in "the parish church". 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. He told historian Reuben Potter in 1861 that the site was in a peach orchard near the mission. Twenty-eight years later in correspondence with Hamilton P. Bee, Seguín remembered placing the remains in a tomb inside the "Cathedral of San Antonio". Remains believed to be those of the Alamo defenders were discovered at the Cathedral of San Fernando in 1936, the battle's centennial. Time had decayed their original container, and they were re-interred in a marble sarcophagus. Purported to hold the ashes of Travis, Bowie and Crockett,