The Texan defenses at the Alamo suffered from several critical vulnerabilities that ultimately led to their defeat in 1836. First, the garrison was far too small; with fewer than 200 men, they were tasked with defending a sprawling mission complex designed for hundreds more, leaving many sections of the wall undermanned. Structurally, the Alamo was a mission, not a purpose-built fortress; the north wall was particularly weak and prone to crumbling under artillery fire. Furthermore, the Texans lacked a "professional" unified command, as tension between regular army leader William B. Travis and volunteer leader James Bowie initially split the men's loyalty. Perhaps most fatal was the lack of a cavalry force to serve as scouts; without "eyes" in the field, the Texans were caught off guard by the rapid winter arrival of Santa Anna’s massive Mexican army, cutting off any hope for effective retreat or the arrival of significant reinforcements from other Texas settlements.