Castillo de San Marcos National Monument in St. Augustine, Florida, claims to be the oldest fort in the United States. But just as St. Augustine is not the oldest city in the U.S. – that distinction goes to San Juan, Puerto Rico – Castillo de San Marcos National Monument is the oldest fort only among the 50 states.
Castillo de San Marcos was built by Spanish explorers beginning in 1672. By contrast, Castillo San Felipe del Morro (“El Morro”) – located in the U.S. territory of Puerto Rico – was also built by the Spanish, but its construction began in 1539, more than a century earlier. El Morro is in fact the oldest fort within the U.S. and the oldest Spanish fort in the New World.
More superlatives
El Morro is a National Historic Landmark, and its webpage from the National Park Service includes more superlatives than just “the oldest.” It is also “the most iconic fortification built by the Spanish in the Americas” and “the most feared of all the Spanish colonial fortifications.”
It was built in San Juan Bay, “one of the best harbors in the Caribbean,” as a typical Medieval castle, but over the years it was strengthened and enlarged to encompass six levels of masonry, impervious to cannonballs and deadly to invaders.
Defense
In 1595, Sir Francis Drake attacked El Morro, but was rebuffed. In 1598, George Clifford, Earl of Cumberland, successfully attacked from the land side of the fortress and took control of Puerto Rico for the British.
Cumberland brought a fleet of 20 ships and approximately 1,700 men to bear against Puerto Rico. They attacked by sea and by land, and were able to penetrate the defenses of El Morro from the land while Spanish forces were distracted by the bombardment from the sea. This was the only time in history that the fortress fell to an enemy force.
The British sacked San Juan and plundered the city, destroying much of the infrastructure. After 65 days, however, the British invaders were so decimated by dysentery that they were unable to hold their position any longer. Cumberland and his men had to give up and escape by ship.
The failure of the British in Puerto Rico caused financial distress for their investors and for England. Some historians believe that this experience caused England to back off on their plans in the Caribbean and to look to North America instead.
As for Spain, the brief loss of Puerto Rico caused increased investment in El Morro, which was further built up and strengthened. Spain reinforced their military presence in Puerto Rico with additional ships and troops. The Spanish Crown implemented measures to strengthen its control over Puerto Rico and its other Caribbean colonies. This included reforms in governance, taxation, and trade policies.
For example, trade was limited to Spanish ships and at some points even to specific Spanish companies. The increased military presence was intended to ward off foreign invasion, but also to strengthen Spain’s control over the colony. Taxation was increased, and Puerto Rico became one of the most important strongholds of Spanish power — economic and military — in the Americas.
In 1625, Dutch invaders attacked Puerto Rico. At the time, Spain occupied the Netherlands, and this conflict was part of an independence movement among the Dutch, known as the Eighty Years War. The Dutch were unable to breach El Morro. They lost 200 men and some ships, and they set fire to San Juan on their way out.
Reinforcement
After each attack, El Morro was fortified and strengthened. The gradual improvements in the fortress continued until 1797, leaving El Morro as a showcase of the advances in military engineering. In that year, the citadel rebuffed another British invasion.
The next active military episode was the Spanish-American War, in which the newer technology of the U.S. military was found to be a serious threat to El Morro. The fortress was later an active military installation for the United States during both World Wars, known as Fort Brooke until it was retired in 1949.
Now, El Morro is a major landmark for Puerto Rico, an important resource for historians, and the most popular tourist attraction on the Island as part of Puerto Rico’s World Heritage site.
