On the Labastida map (Figure 4), the defenses of the north courtyard are described as a foso interior (straight trench) and a bateria a barveta (battery in barbette) with a foso exterior (the circular trench). Sanchez-Navarro adds there was also a banquette along the interior of the wall, and Filisola implies one was present. Since this was the usual practice, we assume one was present.
The straight trench is much too deep to have been intended only as the supply of earth for a banquette along the north wall. The excess had to be used somewhere, and the most likely place is on the outside of the wall for the construction of another standard part of a defensive structure, a parapet of earth to protect the wall from cannon fire.
The straight trench would normally have been placed outside the north wall where it would serve as a greater obstacle to an attacker. The fact that it was placed inside the north wall argues the wall was too low for the effective protection of those defenders not actually on the banquette. Inside the wall, the trench gave an area behind the wall of sufficient depth for troops to maneuver in relative safety.
There is, as yet, no indication of a similar trench on the east line
of the original courtyard, and certainly Labastida shows no such trench.
The excavations of Mardith Schuetz along this side in 1973 would probably
have found such a trench had it been present. The absence of a trench implies
the wall may have been considerably higher here, and needed no defense
beyond that supplied by the cannon positions in the corner of the courtyard
and the top of the church, which also would have protected this wall line.
No evidence is yet available to permit us to determine whether freestanding
walls were in this area before these defenses were constructed.
Developments after 1836
The U.S. Army
The U.S. Army may have been responsible for the wholesale leveling of the courtyard some time after 1836. Certainly little easily recognizable evidence of the army occupation remains, at least in the areas examined during these excavations. The third ditch feature encountered in Units EI and EII was apparently excavated by the army and refilled at a later time, then a wooden structure was built in the area. The army ditch is a good deal more irregular than the underlying circular trench. The available evidence indicates the army ditch was probably straight and ran roughly south along the U.S. Army/Samuel Maverick property line.
The ditch may have been dug about 1847 to aid drainage of the stables built by the army in the courtyard, and filled in about 1851 when an official leasing arrangement was reached with Maverick, giving the army more area south of the line of Houston Street. The footing trench which crossed this filled ditch may have been for the first version of the large wooden building which eventually shows up in Koch's 1873 bird's-eye view of this area. No records are presently available which would provide details of when these buildings were constructed or exactly where they were.