How was such a small number of Texans able to defend their position for as long as they did?

Answer 1

Because the Mexican Army did not make the mistake of advancing on the Alamo during periods of daylight until much of the defenders ammunition had been depleted. The rifles in the hands of the Texans were far superior to the Brown Bess musket that the Mexican troops were armed with so they avoided becoming targets and remained out of range for most of the siege. When they made their attack they simply kept advancing until the most effective weapon was a bayonet. From the start of the attack until the last defender was dead required only one hour.

Answer 2

The "Thirteen Days of Glory" requires at least a tidbit of historical accuracy beyond the John Wayne depiction of the "Alamo". (It was truly a heroic effort on the part of the Texas Army. That much is certain.) The actual Battle of the Alamo lasted no more then one hour from the moment the attack was launched until the last defender was dead.

The Siege of the Alamo, which included numerous exchanges of artillery fire is what lasted for 12 days. It was broken by at least one three day truce during which no fire was exchanged. Some of the women and children who had taken refuge in the Alamo elected to return to their homes at that time. Some chose to stay.

From the time of his arrival, Antonio Lopez de Santa Anna maintained a loose perimeter of Dragoons and Cavalry surrounding the Alamo complex. This was designed to prevent individual and collective escape and to prevent re-enforcements from joining the defenders.

It was not a tight enough picket line to prevent numerous couriers from riding out and through the lines and at least one made it out, returned, and slipped out again. A few reported that they had tried, but had been unable to return which may indicate that the pickets were more intent on preventing re-enforcements. There were at least 18 men who had been sent out and survived. It seems unlikely that if the pickets had killed or captured any couriers they would not have paraded their dead bodies before the Alamo defenders.

Another factor that may have prolonged the survivability of the Alamo Defenders was the quality of weapons and munitions. The Mexican Army had delayed their attack to allow stragglers, their heavy weapons, supplies and follow up troops to join with their main body. They had adequate artillery, but their powder was so inferior that the guns did not have either the range or the punch needed to destroy the Alamo's improvised fortifications. Their primary infantry weapon was the Brown Bess musket which was no match in range and accuracy for the hunting and sporting rifles in use by most defenders.

Answer 3

The Alamo was in a state of siege but was not under attack until 6 March 1836 and even three days of the siege included a three day armistice during which some of the women and children who had sought refuge in the Alamo returned to their homes. If the Mexican Army had elected to occupy the Alamo they could have done so at any time they wanted to. When they did make their assault, the last defender was dead within one hour.