The final stone construction of the bastions (projecting fortifications) was similar to the presidio construction. The temporary adobe structure created immediately upon arrival was replaced later with stone. However, unlike the other presidio structures, it is believed the bastions were rebuilt twice before finally being built of stone.
Although effective, the bastions were not perfect. The southeast bastion had a lower rooms with two cannons, but it was so small that the men risked suffocation from cannon smoke whenever the cannons were fired. Given their position, the adjacent walls were not fully protected and the men were dangerously exposed. The upper level might have had three cannons, as did the northwest bastion, which was filled with earth nearly to the top. Although they were better positioned, poorly constructed low parapets limited the soldiers' protection.
The design and position of the two bastions made them in the words of one historian, "quite capable of effective defense of the fort." The presidio was attacked on several occasions, and the artillery batteries, located in the two corner bastions, played key roles in warding off attackers. It is believed that there were a total of seven or eight cannons comprising the bulk of the presidio's armament.
(Upper Left Graphics
Artist's conception of the original bastion. Artwork by Beverly Hatchett
Artist's conception of the bastion as rebuilt by Rabago in 1761. Artwork by Beverly Hatchett
Artist's conception of the stone bastion based on evidence. Artwork by Beverly Hatchett
(Lower Left Graphic Caption)
Cutaway illustration of the southeast stone bastion shows a lower level interior room. Artwork by Beverly Hatchett
(Right Images Captions)
Northwest bastion, round in shape, was filled with earth up to near its top and featured loopholes for the cannons. Photo courtesy of Matthew Kaser
Southeast bastion, square in shape, ws multi-leveled. Photo courtesy of Barry Wagner