Spanish Fortifications in the Caribbean: St. Augustine, FL and San Juan, PR (by Nathan Hudson)

During the golden age of the Spanish Colonial Empire, the Spanish transported large amounts of goods, bullion, slaves and soldiers in, out and around their New World colonies. They did this via their trade systems throughout the Caribbean, Gulf of Mexico and Atlantic and Pacific Oceans. Early on in the lifespan of the empire – sieges, raids and attacks by rival European powers and pirates were common.^[1]  These ships and port cities would need a strong line of defense against these threats, not only to protect their goods and trade routes but their city and colonial subjects as well. This is where the colonial fort system came to be. Major forts began to be constructed throughout the Caribbean in places like Puerto Rico, Cuba, Panama and Colombia.^[2]  Outside of the Caribbean, similar forts were built in places such as Veracruz, Mexico and St. Augustine, Florida – as all of these places played a crucial role in the protection of Spanish goods and property. One such fort that was constructed, and still exists today as it is extremely well maintained, is Castillo de San Marcos in St Augustine, Florida.

Castillo de San Marcos in St. Augustine is the oldest standing fort in the United States. Its origins date back to October 2nd, 1672 when Florida governor Manuel Cendoya broke the ground for its construction. For many years, only wooden forts guarded the town of St. Augustine. These forts were old, dilapidated and falling apart with wood so rotted that it could not hold the weight of a cannon. St. Augustine did not have the capital to build a new stone fort, as they barely had money to trade and the town was considered destitute, diseased and starving. This lack of defense came to be problematic when in May 1668, a pirate ship masquerading as a Spanish relief convoy infiltrated St. Augustine and sacked the town under the cover of night and killed 60 people. This attack finally prompted ships from New Spain and Havana to deliver the aid that the town desperately needed and convinced the Spanish that stronger defenses were needed to defend themselves. By 1671, Governor Cendoya was appointed to lead the colony. Him and engineer Ignacio Daza immediately made plans to construct a new fort, with construction beginning in 1672. ^[3] Over the course of 23 years, the fort was steadily constructed, but faced financial setbacks, lack of political support, pirates, disease and starvation of its laborers. By 1695, the fort was finally complete. A monumental Spanish achievement of defense in the New World. One that would prove to stand the test of time and attack.^[4]

Castillo de San Marcos is made of a rare limestone-type material found only on the Atlantic coast of Florida. Coquina, as it’s called, is the result of thousands of years of coquina clam shells piling on-top of one another and upon exposure to carbon dioxide, dirt and vegetation, the carbonic acid would dissolve and essentially glue the shells together and form a durable but porous limestone. This material due to its porous nature would absorb the shock from an impact such as a cannonball. This would essentially leave  the limestone unharmed, as other building materials like brick or concrete would shatter on impact. This unknown material became the best defense in the Florida colony, and the Spanish had access to it in abundance. The fort is contemporary for its time, with walls made of coquina up to 30-feet high and 12-19 feet thick depending on which side is facing the ocean.^[5]

This new fort was to be the first line of defense of the colony, protecting not only the town and its residents but ships passing in and out of the New World. Trade through and from St. Augustine was critical to the survival of the colony, and Castillo de San Marcos played a crucial role.^[6] Prior to the fort’s construction, from 1578-1610, St. Augustine imported almost 900,000 reales worth of goods through the intercolonial trade system to help sustain itself. This number alone demonstrates the sheer amount of wealth and goods passing through the small colony by the sea. In return, especially after construction of the Castillo, St. Augustine provided protection from ships sailing to Spain or the Caribbean. British privateers and pirates were common throughout the Caribbean and off the coast of North America and St. Augustine was a brief place of protection from ships being attacked and raided. Being that St. Augustine’s closest trade partner and ally was Havana, Cuba, their economies were tied heavily and Havana supplied St. Augustine with goods, soldiers and labor.

Castillo de San Marcos would endure two major sieges during its time under Spanish control prior to British occupation in 1763. The Sieges of 1702 and 1740 both saw the British Empire laying fire upon the massive coquina monument, and neither time the fort gave way to its British invaders.^[7] One British officer even recalled how the fort suffered little damage after the month-long siege in 1740 (see timeline for more information on both sieges).^[8]

Castillo de San Marcos was the first line of defense for the colony of St. Augustine, with a unique architectural material and has the distinct honor of being the oldest fort in the United States. The Castillo still stands tall and proud today as an important cultural and historical landmark and it is managed and maintained by the National Park Service.

Timeline Bibliography – Castillo de San Marcos

Figure 1. Ningyou. The Cross of Burgandy. March 6, 2006. https://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Flag_of_Cross_of_Burgundy.svg/800px-Flag_of_Cross_of_Burgundy.svg.png?20240718180822.

Figure 2. Metilsteiner . Pedro Menendez de Aviles . June 13, 2014. https://commons.wikimedia.org/wiki/File:FAIRBANKS(1858)_p136_Menendez,_Founder_of_St._Augustine.jpg.