Defensive Trenches

Glenn,
The short answer is that we don't know for sure....which puts us into the realm of what Jake Ivey calls "informed opinion." Informed opinion means that we read every detail about the subject, digest it, balance what is written against what we know from archeology, or similar architecture (other missions) in the region, then and only then, do we dare to speculate.
As you know, the trouble with Navarro is that while he did show us some of what DID exist, he also placed features where there were none (as in the outer defensive ditch at the SW corner, NOT found during the "Radio Shack" dig.) On the other hand, he can be verified in other areas as accurate. It seems that, as with the banquettes, he showed them where they were (northern wall of the north courtyard), and then got ambitious and placed them where we know they weren't (Eastern wall of the same courtyard). So the problem becomes: What do you believe?
Of course, much of the question could be answered by simple archeology. Look at the "planter" that outlines the Low Barrack. It is only grass. Why not do a simple dig or two there? Remnants of the lower reaches of any such ditches would probably be found. At least, this would clear up the issue of diches in the Low Barrack.
I do recall that some Mexican source other than S/N mentioned these ditches, I think in the Long Barrack area, but offhand I cannot recall who at the moment. Digging in the Granary section, or Long Barrack areas more to the south, would answer the ditch matter there, but good luck getting clearance with the DRT.
I think it is safe to place them in the Long Barrack section, at least in some of the rooms. The reasoning was, I feel sure, that the ditches could be a refuge area when and if the barracks areas came under direct fire from cannon, which is ultimately what happened. No doubt many, if not most, defenders in this area retreated down into them, and some may have been tempoarily saved from the flying splinters, but when the Mexican infantry forced entry, they were like the proverbial rats in a trap, fighting from "down low," instead of "up high."
As for the question of enough area to sleep, that is an excellent, insightful question, and one with which I grappled for a time when doing my drawings for the book. The interior width of these Long Barracks rooms was between 13.8 and 14.0 feet. If you dig a 3 foot wide ditch down the length of the room, that will leave you only about 11 total feet (didvided by 2, equals 5.5 feet). With 5 and a half feet on each side, it is possible, but surely not very commodious, for men of that era, with an average height of what? 5'3"? to sleep. I'm sure that they had sections of boards placed across the ditches at intervals, as improvised "bridges," across which to walk, saving them from having to jump across, or climb down, then back up, every time they wished to cross.
When they were dug is not known, but your guess is as good as mine.
I feel sure that they were dug for the reason S/N states. he goes into some detail in his complete translated version of the key to that map, and the purpose seems pretty straight forward.
Mark

It probably depends on how literally we take Sanchez-Navarro. I'm certainly unhappy with the curious notion of digging trenches inside buildings in the 1830s, and I did speculate on another thread whether they should be actually interpreted as some kind of fire-step constructed within the unroofed(?) jacales to the north of the long barracks.

Mark rightly counters of course that Sanchez-Navarro also depicts them inside the long barracks and low barracks, but both my own feelings and your comments rebel against this; and I still consider that his annotations are being interpreted too literally and that what he's really indicating is not that there was a ditch running through the floor but that the lower rooms had been fortified.

The breastworks described by Potter, presumably on the authority of eyewitnesses like Ruiz would have been an obvious part of this and if set slightly forward of the door or slightly back from it, like the blast wall on a modern bunker entrance, would allow defenders to slip in and out, but at the same time protect those inside from direct fire - or a rush by attackers

Many thanks, Guys. Some great comments. It does appear, at least for the time being, that some questions will remain.

Rich. I agree with your view of the trenches as "lunacy." No doubt the Texans thought it was a good idea at the time...as long as all the cannon were spiked, that is. And yes, "The Alamo" (2004) did make the defenders in the trenches look like, as Mark says, "rats in a trap." I wonder how much longer they could have held the Long Barracks had they spiked their cannon.

The question in regards to the semi-circular breastworks Potter described has always puzzled me - inside the door or outside? And the big question: did they really exist at all?

Glenn

Well that seems clear enough, Foso is verly clearly derived from fosse; but I wonder if part of the problem here is that image of continuous run defensive trenches as depicted in Alamo2004.

If SN is to be taken literally we're really talking about the equivalent of shell-scrapes and the like, purely as a refuge from anything solid piercing the adobe walls during a bombardment, rather than fortifications.

The purpose of the trenches was as a place of relative safety if artillery was turned upon the jacales. Actually, the trenches do make sense under a very specific scenario, i.e: The defenders retreat into the relatively weak-walled jacales, and dive into the trenches, as the Mexicans turn the captured guns upon them. The blasts of grape would shatter the jacale walls, but most of the defenders would survive. The Texians could theoretically then fight from a ready-made entrenched position, now that the jacale walls were largely blown down. Thus, the ditches served two purposes, a safe haven from artillery, and a defensive firing position after the initial blasts. But no plan survives after the first round is fired, as they say......This from de la Pena:
"The terrified defenders withdrew at once into quarters placed to the right and the left of the small area that constituted their second line of defense. They had bolted and reinforced the doors, but in order to form trenches they had excavated some places inside that were now a hinderance to them..." While I don't doubt for a minute he is right, it would be nice to know EXACTLY what he meant by " were now a hinderance to them.." WHY were they a hinderance? Did he see, or hear about defenders who fell backwards into them as they were trying, madly and in the dark, to defend themselves? Did the trenches get in the way of men trying to move rapidly from point to point inside the structures? Or were the defenders, once the Soldados were upon them, just "fish in a barrel?" One thing is certain. While the ideal scenario might have looked good "on paper," when you put men in a low, open defensive position, with an aggressive and motivated assaulting force of infantry coming at them quickly, with bayonettes, standing low in a ditch is the last place you want to be. The rule of thumb is usually, the higher the defensive position is, the better.