Colonel Ugartechea commanded a unit of cavalry that slipped through the siege forces on November 12 and made its way in about ten days to the Rio Grande (Río Bravo) to seek reinforcements. On November 26 he guided a force of 454 conscripts and 173 veteran troops from Laredo to relieve the centralist army under Cos at Bexar. Their arrival on 8 December actually increased the burden of supply on the centralist army and helped to precipitate its surrender on December 9 to the Texans.