Once he was in San Antonio, the town and Cos' men were besieged by the Texian Army under the leadership of Stephen F. Austin. After a 56-day siege of the town and the Alamo Mission, on December 9, Cos surrendered San Antonio de Béxar and its weapons to the Texians, then proceeded to retreat back across the Rio Grande. Cos and his men were allowed to keep their muskets for protection, as well as one four-pound cannon. Mexican losses during the siege were about 150. On his way south, Cos met up with Santa Anna's forces at Laredo, who were marching north to put down the rebellion.