The Great War was merciful to the town surrounding the Alamo and the city of San Antonio. Only one bomb fell, blasting the northern part of the town into a crater. The Alamo itself by chance, was completely untouched. About fifty years after the end of the War, the Brotherhood of Steel moved in, making it their main base of operations for Texas.
If the player character sided with Keats in Austin they will be sent to the Brotherhood compound, which is under siege from the Twisted Hairs. They will meet with Paladin Haig and be briefed and charged with taking out Harpy, the leader of the Twisted Hairs.
If the player character sided with Shale in Austin they will be sent to aid the Twisted Hairs in their attack on the base. They will meet up with Harpy, be told about the invasion and charged with getting into the compound and taking out Haig.