(The following is based on reporting by Our Traveling Reporter, who’s been too busy to attend more shooting schools, as a student, anyway; but he has gotten some sightseeing in and deluged us with photos. We’ll be using the categories Fortifications and Historical Places to collect these stories in the weeks and months ahead. This is only the first of several photo-intensive posts on the Castillo de San Marcos — Ed.).
The Castillo de San Marcos — in English, Castle of Saint Mark — was a Spanish fortification meant to defend Spanish America against threats — spelled: Englishmen. This remarkable National Monument is little known by most Americans, but it’s one of the most interesting (as we’ll see in a future post, not the most interesting) military history sites on the northeastern coast of Florida, a peninsula that’s seen many flags and many fights over the years.
The Technology of the Fort
The Castillo is a fortification of stone on a typical 17th Century Vauban system (albeit, with some subsequent improvements). It looks to the casual viewer like a medieval castle, but it is a highly developed gunpowder-era fortification for fighting wars against sailing ships and land forces armed with the best cannon of the 17th and 18th centuries. The local stone, called coquina, is a sedimentary stone or limestone formed in large part of seashell fragments and sand. It is an almost ideal fort-building material: soft and easily formed when first quarried wet, but hardening to a concrete-like consistency after some months or years of air-drying. It proved to be very resistant to bombardment. Instead of shattering under cannon fire, the coquina blocks seemed to absorb the cannonballs. Twice, this led besiegers to give up and depart.
Spain constantly improved the technology of the fort, raising the walls and the bastions, and vaulting the interior rooms to allow heavy guns to be moved anywhere along the walls rather than just in reinforced areas.
Castillo de San Marcos, view generally North to South
The design of the fort is regular, symmetrical and repetitive for a reason. The advent of gunpowder caused a reassessment of fortifications that had been adequate in the day of weapons powered by muscle and sinew, and primitive, rock-throwing siege machines. The Elvis of fort design was a military engineer in the service of Louis XIV of France. The Sun King’s fort man, Sebastien le Prestre de Vauban, came to Louis as a captive, but changed sides, and went on to display his mastery of taking forts — and building them so as to make taking them difficult.
The Castillo strongly resembles a medieval castle, which makes sense when you think about it: even its name means “castle.” The Middle Ages are generally considered to end somewhere in the middle of the first millennium AD, and this fort began to be built shortly thereafter. Its basic shape is a rectangle, with a parade ground inside. Four diamond-shaped strongpoints called bastions provide mutually supporting fire and ensure that every wall exposed to an attacking enemy can be swept by fire.
The corner bastions allowed cannons, musketeers and archers to cover the long walls and take any assaults under enfilading fire. When the fort was originally constructed, the bastions, three of which are solidly filled inside (the fourth is solidly filled, apart from a vaulted powder magazine), were the only part of the structure that could support the weight of cannon.
A fifth “bastion,” an irregular heptagon, is the ravelin, a structure that provides the only way in and out of the fort, and that protects the gate in the fort wall from observation and direct fire. The NPS calls it a demilune, the difference between the two being somewhat hazy in military engineering.
The seawall is part of the overall fortification model, and is made of an inner and outer wall of the same coquina that built the fort, stuffed with rocks and earth. The coquina blocks are set in ashlar and the wall was topped with granite, providing a promenade in peacetime and a firing position in war. The initial wall lasted a century; it was rebuilt by West Point-trained engineers during the US Territorial period after Spain ceded Florida in 1821. (They used the same materials as their Spanish predecessors. Don’t mess with success). That wall lasted, with some deterioration, until powerful hurricanes in the 21st Century damaged it; a rebuild project is underway to protect the historic wall with a modern concrete wall to seaward.
The landward sides of the Castillo were protected by a glacis of earth, designed to stop cannonballs or deflect them over the fort entirely. The fort side of the glacis terminates in a retaining wall, creating a covered and concealed pathway allowing defenders to move without being exposed to observation and direct fire. This is called the covered or covert path. In times of war, additional works of earth and would be constructed out beyond the glacis, providing further defense in depth.
Moat, shown on NPS brochure. Definitely worth a click to embiggen.
There is also a moat, which nowadays seems to be kept dry deliberately, but which was flooded originally and at least as late as our first visit in 1974. The moat flooded tidally to a shallow depth, but could be flooded deeper through a system of locks and gates. It is one more sign that this fort didn’t just happen, but was engineered in every detail.
A fort implies the potential for siege warfare. Sieges that end in attacker victory usually end, not when the walls come tumbling down, but when the defenders lose heart or run out of food and (especially) water (or the attackers contaminate the water supply). The Spanish builders of the Castillo considered this. They had large storerooms and not one, but three, protected springs inside the castle. (One remains in service today, 350-plus years later). The water table is close enough to the surface — it is Florida, after all — that even if all springs were somehow destroyed, a new one could be quickly established.
The Spanish considered their faith a bastion against defeat by loss of morale (there was always a religious subtext to Spanish Catholic wars with Protestant England). They incorporated a chapel in the Fort’s design and named its prominent features after Catholic saints, to whom they prayed for Divine intercession.
Sieges that end in defender victory, conversely, usually end when the attackers lose heart, run low on supplies, or are attrited (more usually by disease and malnutrition than by enemy action), although sometimes a relief force lifts the siege by defeating the attackers or leveraging them out of position.
History of the Fort
The Spaniards began constructing it in the 1660s, after a previous wooden fort was burnt and the town sacked by pirates, and the first stone was laid in 1672. We know the name of the engineer who was sent from Spain to design and supervise the construction of the fort, Ignacio Daza, although we know little else about him. The fort was completed — to the extent that any fortification is completed — in 1695. It would have been faster, but Daza was at the end of a long pipeline, and even at home, Spain was always short of money and skilled artisans. The Florida coast was not a perfect environment for European life, either. If the pirate sacking of 1688 wasn’t enough, the Spanish were motivated by the new English colony just up the coast at Charleston; they knew that the kings of Europe seldom went long between wars, and when Spain and England warred again, the more-numerous English would come for Spanish America.
When construction began, San Augustin had been a Spanish city for over 100 years. But the growing British strength in the New World threatened San Augustin. The fort was tested soon after its completion by a British siege in 1702. The civil population crammed into the fort, the city burned, but the fort held until a Spanish squadron relieved the city. Trapped between the stronger Spanish fleet and the shore, the British burned their ships and departed overland to Charleston. After a period of some decades of peace, Britain and Spain were at war again in the War of Jenkins’s Ear (yes, that’s really its name. Google is your friend).
In 1740, the British tried again with a better thought out attack plan, but they still wound up defeated by the coquina stone walls.
The Castillo stood against the English for a long time. In the end, it fell not to the sword but to the terms of a treaty dictated after a Spanish defeat on other fields. By the time the Revolution came to the Colonies, it was a British garrison, won by Britain by defeating Spain (a French ally) in the Seven Years’ War in 1763. During the long American War of Independence, Colonial forces never put pressure on the fort, and it was a backwater of the War of Independence. By the Treaty of Paris which recognized American independence, it reverted to Spanish sovereignty. The colony was more of a burden than a boon to a troubled Spanish monarchy, and the United States purchased it from Spain in 1821. It flew the Stars and Stripes for the next 40 years, becoming a Confederate fortification without a fight in 1861, and reverting to the Union just as peacefully in the spring of 1865 on the defeat of the Confederacy. Throughout the 19th Century, it was widely used as a prison for Indians, both from the Seminole Wars and plains Indians, removed to Florida, far from their supporters. During the Seminole War, these Native Floridians cemented their reputation as hard cases — it was the most costly Indian war from the whites’ standpoint — but most of the native American prisoners here were Plains Indians. It seems that important chiefs were sent to San Marcos. It was the Gitmo of its day, or perhaps Alcatraz for Indians.
When the Castillo de San Marcos became part of the US coastal fortification system, like all the forts in the system, it had periods of improvement and periods of stagnation, if not neglect. The American owners filled in the part of the moat between the fort’s eastern wall and the seawall, and used it to site a battery of then-new Parrott guns, extending the fort’s reach to sea. To increase the guns’ threat to the wooden sailing warships of the day, a stone furnace was built behind this battery to heat shot red-hot, adding the threat of shipboard fires to the woes of any attacking naval squadron.
By 1933 it was a white elephant burdening the US Army. Coquina is awesome stuff, but it wasn’t made to withstand breechloading artillery; new concepts in coastal defense used smaller, concealable, reinforced-concrete gun emplacements linked by electric communications to remote observation and fire-control facilities, integrated with command-armed and -detonated minefields air patrols. Furthermore, the Indians were off the warpath for good, and Americans had no stomach for locking them up. With no practical use in hand for the old fort, and a Depression squeezing everybody, they pushed it off onto the Department of the Interior. Now it is a national monument, maintained with pride by the National Park Service.
It has also been recognized as a civil engineering monument by the American Society of Civil Engineers. One doesn’t think much about the technology that went into building a mighty fortress in the centuries before steam, but the Engineers apparently did.
You might wonder, in all those different phases of ownership, how many times the Fort has been abandoned, derelict, in ruins, or restored. The answer is — none. The Castillo withstood the attacks of 1702 and 1740 with aplomb, and perhaps more impressively, has shrugged off centuries of assault by the elements. All of the fort’s many changes of flag have been done peacefully, as a result of wars decided or treaties contracted in other places. The Park Service has done some excavation and restoration to the grounds, and keeps up with the maintenance, as the Army did.
Conversely, an out-fortress at Matanzas, built after the 1740 attack, was allowed to go to ruin, but has since been restored.
After the For More Information section below, there’s a “more” button — and with it, you’ll find some photos taken at Castillo de San Marcos recently by Our Traveling Reporter. We’ll have more photos, and more information links, in future reports.
This post has been corrected. We had used both terms ravelin and demilune without making it crystal clear we’re applying them both to the same structure, the low bastion-like element that guards the approach to the sally port. NPS prefers demilune.
For More Information
Fortified Places: http://www.fortified-places.com/
The terminology of a Fortress: http://www.fortadams.org/bDiscoverbTheFortress/TheTerminologyofaFortress.aspx