Texians believed this pledge was broken when Cos returned in the spring of 1836 to command a column in the attack on the Alamo. On April 21, 1836, he reached San Jacinto with reinforcements and crossed Vince's Bridge just before the Texians destroyed it. He was taken prisoner by Sam Houston in the general surrender and later released, after which he returned to Mexico. Cos later commanded a post at Tuxpan during the Mexican–American War. He died in Minatitlán, Veracruz, in 1854, while serving as commandant general and political chief of the Tehuantepec territory.