I was inspired by a Seth Eastman painting of the north side of the connecting wall between the church of the Alamo and the Convento. You can see the Watch Tower on the hill in the background.
The face of the wall is about was about 10 degrees east of true north and was able to catch only a few minutes of direct sunlight at dawn on a summer day as this painting seems to depict. A sketch of the same scene is dated November, 1849 but this painting must be from summer as there is no direct sunlight on the wall at that time of year.
This render using the Cycles engine in Blender was done in 240 frames for a simulated June 1849 day. The Blender Sun/Sky plugin was used for generating the lighting. The particle system was used for the background trees, grass and stones. The picket fence was done using a new technique for me that combines the array modifier and the particle system to generate a linear array of element picked at random from a group. The wall textures were created from photos of the Alamo church and Long Barrack that I took on a trip to San Antonio a few years ago.