Exploring Castillo de San Marcos

Welcome to Part II of this somewhat open-ended series. In Part I, we introduced you to the history of Castillo de san Marcos in Saint Augustine, Florida. This well-preserved Spanish fort, itegun in the late 17th Century, is a rare sight in the Continental United States.

This floor plan is posted on the site by the Park Service. Click to enlarge. The sea -- the greatest threat -- is to the right. The walls are thickest there.

This floor plan is posted on the site by the Park Service. Click to enlarge. The sea — the greatest threat — is to the right. The walls are thickest there. The demilune is not on the map, but the drawbridge at bottom center goes there.

The fort had several distinct periods of occupation, by Spanish, English, and American (including Confederate) troops. It became a key component of US defense in part due to the brilliance of a young engineering officer, then-2nd Lieutenant Henry W. Halleck, who gave a series of influential lectures at the Lowell Institute in Boston in 1846, where he argued the fortification’s superiority over the naval attack, using many in-depth examples. Despite his low rank, Halleck had high patrons and his views revitalized fortifications in the inter-war period. (If you recognize the name, it’s because he served uncomfortably in several high commands in the Civil War before finding his true calling as Grant’s Chief of Staff).

So let’s continue our photograph tour of this fascinating site!

There will be two photographs here to warm up, then the bulk of this photo-rich post is after the jump. (Notes and References are found there as well).

Originally, the many rooms or casements of the Castillo — there are 29, counting one that was later bored into the earth and stone fill of the northeast bastion as a powder magazine — had straight walls and high, flat ceilings underneath the floor of the upper gun deck. The problem with this was the guns were limited in weight, unless they were positioned right above a load-bearing wall. Larger shipboard and fortress guns could weigh many tons. So, when the Spanish still held the fort, between the sieges of 1702 and 1740, they vaulted these ceilings. The arches gave the floors above more support for heavy guns, not to mention increasing the protection of the contents of the casements — whether those contents were soldiers, displaced citizens of St. Augustine, or supplies.


Yes, PFC, in those days soldiers slept in an open bay. This wasn’t the cultural trauma it is for today’s basic trainees — lots of people did that at home, too, especially in the lower classes whence enlisted soldiers came.

In combat, these casements might also house cannon and the window become a firing port — but the primary sting of Castillo San Marcos was always on its upper deck.

There are some fascinating period graffiti on the walls. They are protected, now, by plexiglas which means that they’re hard to photograph, but we’ve tried to enhance these to the point of legibility. Best guess at this time is that this ship was drawn by a Spaniard, representing the Royal Navy ships that occasionally exchanged cannon fire with the fort. Several of these ship drawings have been found. The ship is traveling from right to left, with its high counter on the right and the prow, nearly faded out, on the left. The small dots are the guns. Some time after 1821, American soldiers added a huge American flag; it and the masts and sails are not evident in this photo.


Archaeologists have fun with these 18th and 19th Century equivalent of caveman paintings!

The curators point out that the “checkerboard” look of the graffiti suggests the ships were British. British ships around the turn of the 19th century were painted with alternate white and dark stripes, with the white stripe running along the gun ports. Opening the gun ports and running the guns out was often threat enough to get a smaller ship to strike her colors (surrender). To an equally sized or larger ship, it was an invitation to fight.

More after the jump.

Here’s a picture of the whole “grafitti wall.” (Complete, unfortunately, with ghostly reflections). The ship we just saw in detail  is in the lower left, and another one is in the upper right.


Under the mercantilist theory of economics and politics current at the time of the Enlightenment, four major European maritime powers (England, Spain, France and the Netherlands) played a power game for control of colonies, sea lanes, shipping and cargoes. The colonies provided both materials and markets to the home country. Alliances formed and broke up; in the end, England dominated the seas.


Here’s another graffiti ship — we promise, the last for a while. Is that the prow on the right? The question is, do the crosses on the masts represent the spars that hold the sails of a classic square-rigger? Or are they the crosses of the Christian kings of Spain? The experts think, they’re the rigging.

Forts were vital to the protection of ports, not only from hostile navies — communications being what they were, a garrison’s first alert that peace was over was a hostile fleet showing up offshore — but from pirates and privateers. While having a superior navy let you take the war to the enemy, no navy was big enough to defend everywhere. That fell to shore defenses, which were, in most cases, sufficient.

The garrison soldier’s life was remarkably similar for a fortress defender at any time during the operational history of the fort, as this display from the Parks Service makes clear:


Actually, we would postulate that what permeated the soldier’s life, during any of those periods, was boredom and stultifying routine. He needed to be there to have, to make a small pun, a fort in being; but the deterrent effect of the garrison wasn’t good for the garrison. Leaders, particularly NCO leaders, would have done all they could to keep the men busy. Fort maintenance and beautification duties would have been one method used here, “mindless details” or “fatigues” as soldiers always have known them. And training, which in the period from the 17th to the early 20th Centuries would have been predominantly rote drills, would have occupied some time. Good leadership made the difference between miserable, mutinous troops and happily grumbling ones — same as today.

Of course, a mutineer or deserter had few options, at remote San Marcos. On one side was the wet desert of the Atlantic, on the other, pestilential swamps occupied by angry Indians. Whether the garrison soldier was from Castile, York, or Maryland, he was far from home. His most serious threat was disease and the tropical weather.

The Spanish, in fact, had a better grip on medical conditions in the area than the Anglos who followed them here, but that’s another story.

We have mentioned before the construction of the fort from stone named coquina for the little shells that make up its structure. Here’s another hunk of the stuff…


… and here’s how they processed it. While still wet and somewhat malleable, they shaped it with hand tools like this axe. axe

The coquina was used because of convenience — it was there. (Halleck would later observe that it cost a great deal more to construct fortifications in the South than in the North, due to the paucity of materials and skilled labor and the need to ship in both — something the Spanish also experienced). But it turned out to be a fortunate choice, being a nearly perfect material for resisting 18th Century cannon fire.

Apart from the windows/firing ports, the only breach in the hard coquina walls was the sally port. It was sealed with doors: a pair of wide, massive doors through which formations, horseman or wagons could pass, and a smaller inset door for single-file personnel. The doors were removed in the 1950s to protect them from the elements, and are displayed indoors.

This photograph shows the doors at some time during the 1870s.


And this one shows them today. They’re clearly the same doors as the 1870s doors, but nobody seems to know quite how far back they go.


Every meth head in Florida would like to get his grubby mitts on the next artifact — a bronze model of the Castillo. We’re hazy on its age, provenance, and raison d’être, but it sure does look cool.  You’re looking south, with seawards left, landwards right:


The model is a remarkable example of the monument caster’s work, whatever it was made for. It also makes it clear how the entry through the demilune to the sally port worked, in case you didn’t quite get that in the last post:


While there are some nice displays about the anonymous, nameless soldiers of at least four nations (USA, England, Spain, CSA) who garrisoned this place, they left relatively little written information behind (many of them were doubtless illiterate).

But the Great Men of the period did leave a written legacy, and some of them have plaques here and there around the fort. Pedro Menéndez de Aviles was the Captain General of the Fleet in the Indies. Before he could start to set up the Spanish New World colonies, he had to beat their first claimants — the French. As was normal in those days, he went to sea as a midshipman when still a boy of 14. If your family name is Menendez, you just might be descended from this grandee.


If Menéndez was an example of the leadership Spanish blood can produce, O’Donovan was an example of how Spain found friends where she might. Juan O’Donovan, as the Spanish knew him, was an officer in the Hibernia Regiment, a sort of foreign legion formed of men from Britain’s nearest, and most restive, colony. He ran off with the governor’s daughter — a guy with a name like Vicente Manuel de Zéspedes  Céspedes  y Velasco probably didn’t want to wedge some random Irishman into the family bloodline, so he refused his daughter Dominga’s hand. Running off with the boss’s baby girl did not do O’Donovan’s career any good, and he wound up shipped out to a hardship post (Havana) while Dominga sat at home.

Of course, Governor de Zéspedes was a Spaniard as much as a doting father, and even he couldn’t stand in the way of his daughter’s true love forever. After a decent interval, he let his son-in-law come home to St. Augustine.

And so, if your name is O’Donovan, you might be descended from Spanish grandees, too!

Of course, it wasn’t all love and heartbreak on the Florida coast. The Castillo was here as a deterrent, but twice during its Spanish tenancy, deterrence failed and it had to defend. Today, the cannon on display in the courtyard are curiosities for tourists.


The little field piece is cute; easily maneuvered by its crew, it’s meant for close-in land fighting and has very little utility in a ship-versus-fort boxing match. It works the same way as the larger cannon used to defend the fort, but is a great deal smaller.

In 1702, most of the casualties in the fort — three of the four Spaniards killed — were caused by the failure of the breech of this cannon. In recent times, the shattered piece was recovered from the sedimentary bottom of the moat. It is an 18-pounder made of cast iron. The barrel weighed about a ton and a half.


(To our great amusement, the “rustic wood” stand that supports the barrel is all-composite. One of the facts of life in Florida is that it’s prime termite habitat).

This picture of the breach end of the blown gun shows the fracture surfaces.


In its centuries of existence, the fort did its job, mostly, just by being there. But when deterrence failed, men had to man the guns — and take the risks that came with them.


  1. Halleck’s lectures were later collected and printed as a book, now ages out of copyright and available as an e-book from Archive.org, or as a free Kindle e-book. Of the fort, he wrote:

The works projected for the defence of St. Augustine, Key West, Tortugas, and Pensacola will carry some eight or nine hundred guns. Those at St. Augustine and Pensacola are essentially completed, but those at Key West and Tortugas are barely begun.

Most of the forts he mentions in this paragraph were completed — Fort Zachary Taylor in Key West not until after the Civil War — and most, except Fort McRee, one of the four Pensacola works, survive today. All have some historic value, but of these none has the Spanish history of Castillo de San Marcos.


Halleck, Henry Wager. Elements OF Military Art and Science: Or, Course of Instruction in Strategy, Fortification, Tactics of Battles, &c. New York: D. Appleton & Co., 1846; 3/e, 1862. (Kindle edition)

Halleck, Henry Wager (2011-03-24). Elements of Military Art and Science Or, Course Of Instruction In Strategy, Fortification, Tactics Of Battles, &C.; Embracing The Duties Of Staff, Infantry, … Notes On The Mexican And Crimean Wars. (Kindle Locations 1-4). . Kindle Edition.

National Park Service. Various interpretive plaques and installations at Castillo de San Marcos.

10 thoughts on “Exploring Castillo de San Marcos

  1. Scott

    Two typos that I spotted, methinks:
    “a firing port — bit the primary sting”
    They are protected, now, by pleciglas which means

    1. Hognose Post author

      Thanks, Scott. Now they’re fixed, although the spelling I use of plexiglas is with one “s”. I think it was somebody’s trademark circa WWII that way. Corning? Dupont?

  2. S

    Thanks for another excellent article. The rabbit trails these things flush out are most interesting. For instance, Matanzas is Spanish for massacre: that charming Menendez bloke murdered about 350 surrendering Huguenots nearby. That sort of behaviour, and the expulsion of the Jews from Spain in 1492, was the death of the Spanish Empire. King Obama and his little helpers are working hard to add the American Empire to that long list. They never learn.

    1. Hognose Post author

      Yes, that fort Matanzas, which was allowed to go to seed but has been somewhat restored for tourism, is on the site of the Huguenot massacre. Europeans once took that whole Catholic vs Protestant thing deadly seriously. Now, they’re all on their way to enjoying bagged women and Ramadan fasts.

      1. S

        “Now, they’re all on their way to enjoying bagged women and Ramadan fasts.”

        And matanzas; don’t forget the matanzas. If we all still had guns, we’d be a whole lot nicer to each other, but that’s Verboten.

  3. Bonifacio Echeverria

    Very interesting post. I have always wondered, considered that the Spanish literally studded their part of America with elaborate masonry fortifications of trace-italianne (Portobello, Cartagena, Havana, Veracruz…) and the French did also try at Louisbourg, that I can’t see to recall similar elaborate systems in English North America. Did the Brits thought that they had the RN after all and decided to avoid the cost involved or there are any British coastal fortifications pre-1775 of comparable size and complexity to Cartagena or Louisbourg still standing guard in US harbors and cities?

    About the graffitis I would also say they are spars. By the XVIII century Spanish ships had dropped the fad of painting crosses on their sails. It was something of the Late Renaissance, if it was not a fad by the engraving industry of the XIX to depict those colorful sails (modern Portuguese depictions of their exploradores also paint their caravels with crosses in the sails).

    But I don’t think O’Donovan considered Havana as a hardship post at all. By that time Havana was quite a metropolis, it was on his way to being rightly considered as the capital of the Spanish Caribbean (Cartagena permiting) and it had many attractions to errr… hot blooded military young men including scores of rich heiresses of families to turn a blind eye to poor Army officers provided they were of the correct skin color. Spanish professional soldiers didn’t like all that much being posted to America, that’s why the Spanish Bourbons had to rotate their regiments posted there although the rotations being of several years, with the tropical fevers, desertion and the errr… temptations of the land added, usually the rotations weren’t such. Barely a handful of men ever returned.

    By the time they were up to take the flight back to the world most had made their lives there, had married (or brought their families)… or were dead. Usually after a rotation to America, only a handful of men of the original regiment returned, enough to guard the banners so they could recruit another bunch of poor souls to remake the unit by telling tales of the errr… wonders of service in exotic America.

    But if they had to go, they would go very long lengths to try to secure a posting in comfy Havana, Veracruz or Cartagena rather than in (excuse St. Agustine folks there, no offense intended) God’s Forsaken St Agustine. Florida was positively the far reach of the Spanish Empire. As you pointed, only Indians, swamps and fevers to offer. So O’Donovan probably had some very good friends up the ladder (upper than his boss’ anyway) if he managed to tangle with his boss’ daughter and over that get posted to Havana and retain his commission. A story which, BTW, remembers me of the tale of Concepción Argüello, California’s first nun, and the Russian Count… Seems those Spanish gals were burning to leave their dad’s forgotten outposts…

    Also Hiberania was just one of the several Irish Regiments recruited by the Spanish bourbons during the XVIII, among the several regiments of foreigners that made up to a third of the strength of the Spanish Infantry of the line. Not that the Spanish had a “Foreign Legion”. More that a fourth of the Spanish Army was made of foreigners.

    Always short of men, as all the Ancien Regime states, the Spanish Bourbons were fond of recruiting foreign units, provided the foreigners were Catholics, of course, so the Irish did a perfect match. There had been Irish serving Spain at least since the end of XVI century, but by the time of St Agustine the recruitment was more systematic and the units formed part of the regular establishment of the Spanish Army (together with Swiss, Italian and Wallon units all good Catholic chaps, you see). The funny part being that the Spanish recruited mostly the Irish among the expat Irish living in France since the Wild Geese affair, thus competing for such a scarce commodity with the French Army. A great advantage of the foreign regiments was that you could always count on them to quell popular uprisings, no questions asked, which made them quite unpopular at the time among the common folk, although the Irish always enjoyed a greater popularity among Spanish peasants, the Swiss being particularly hated.
    Another advantage of foreigners was that they didn’t know the language nor the customs of the land (at least the first years they spent serving) so for them desertion -that universal common plague of all Ancien Régime armies- was more difficult to attempt and even more the succeed (not so many red heads of blue eyes around in Spain back then…). Even today you can find a lot of Irish sounding names (some castellanised, some proudly mantaining O’s before them) in any roster of Spanish Army officers of the last two centuries. Hell, one of them even made it to President.

    Of all there Regiments, Hibernia was one of the more senior and survived being one of the 3 left by the time of the Napoleonic Wars until it was disbanded as a distinct “ethnic” unit in 1818 out of sheer bankruptcy (the British Alliance between 1808-1812 and the complete dependence of the Spanish Army upon the British supplies and subsidies to wage the Peninsular War probably had something to do too). Hibernia had a long (North)American service, being also at Pensacola in 1781. It was not exactly an élite corps, but certainly it was regarded as one of the shock units of the army as Irishmen tend to end up being considered as in any of the many armies they have ended enlisted into.

    What I doubt is that O’Donovan reached the Grande status (almost a Royal, occupying a very high station in upper nobility). The Spanish Army of the time insisted that you had to have some noble blood to become an officer, and probably the Irish officers were (or claimed to be, nobody was going to write to the British Gov to ask, anyway) some short of gentry or nobility title back in Ireland… but most of them were exiles after all, so dirt poor, that’s why they were soldiering in the first place.

    The status of O’Donovan probably depends on how long had his family been in Spain and/or France. The Irish officers were also well liked by the King, and many that arrived as Spain as destitute migrants made their fortunes serving there, married into Spanish families, not few of them upwards (those Tomjonesque types…), so it is not impossible O’Donovan was well off if he was the son or grandson of an Irish family serving the king, but most probably he had not much more than his army pay to upkeep him and any prospective family (a good reason for the angry dad to resent the crush).

    The main indicator is that he was serving in America, which was a big opportunity for an Army officer to make some money by err… circuitous ways. If he had any, he would probably have spent it trying to avoid being sent there in the first place.

  4. Peter O

    Key West, while not finished, still played a crucial part in the Civil war, as one of (I believe) 4 southern forts to stay out of Confederate hands, and mainly due to the quick thinking of the local Unionist artillery officer, who managed to win the race against his confederate-favoring then-superior and secure the fort.

    Tortugas is a unique day-trip from Key west, being both a massive fort and an Uncompleted fort. Originally planned for 4 stories, 3 of the 4 basement water cisterns cracked from the weight of just 2 stories, rendering the original manning plans impossible.

    1. Hognose Post author

      Fort Jefferson illustrates the change in fort design in the 1800s from the one-level Vauban forts to multilevel forts with great “broadsides.”

  5. staghounds

    1. The Spanish didn’t just paint crosses on the sails, before battle they actually hung big wooden crosses at the mastheads.
    2. “Plexiglas” is in fact a registered trademark, as we found out when the store advertised some custom tack trunks with it on the sides. We got a nasty letter.

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