"Work on the Castillo was begun in October of 1672. A pirate attack
in 1668 and the founding of Charleston by the English in 1670 had prompted the Queen Regent Mariana of Spain to approve the
building of a powerful masonry fortification to defend Florida.
Constructed using coquina rock quarried across the bay on Anastasia Island, the fort took 23 years to complete. A spectacular example of Spanish colonial architecture, the fort was the largest everconstructed by Spain in North America.
The walls of the Castillo de San Marcos were tested in battle in 1702 when Gov. James Moore of South Carolina attempted to capture St. Augustine in one of the major American campaigns of Queen Anne's War. The 1,500 soldiers and citizens of St. Augustine took shelter within the fort and held off the English army for two months until they were relieved by a Spanish fleet from Cuba. Forced to
withdraw, Moore burned the city but became the first of many commanders who would attempt and fail to take the Castillo.
The Spanish strengthened the fort in a second construction project begun in 1738, when they also built walls and other forts around St. Augustine. The improvements came just in time to fend off yet another
English attack, this by Gen. James Oglethorpe and his army from the new colony of Georgia.
Never able to capture the massive Castillo de San Marcos by force, the British finally gained possession of the fort (and the rest of
Florida) in 1763 by the treaty that ended the French and Indian War. The Spanish had sided with the French and lost their American colony when England won the war. Now called Fort St. Marks, the one hundred year old fort was an important British base during the American Revolution. Troops marched north from here to fight numerous battles
against the American Colonists in both Florida and Georgia.
Florida and the Castillo were returned to Spain at the end of the American Revolution. Besieged on the eve of the War of 1812 by a
force of "revolutionaries" from Georgia and the Carolinas, the fort once again served its purpose and protected St. Augustine from capture.
Florida became a territory of the United States in 1821 and the U.S. Army occupied Castillo de San Marcos, renaming it Fort Marion. It served as an important base for operations during the Second Seminole War of 1835-1842 and was used as a prison for captured Seminole leaders. The Native American leader Osceola was held here
briefly before being sent to Fort Moultrie, South Carolina, where he died and remains buried today.
The Castillo itself was considered antiquated by the time of the Civil War, but the water battery built by the United States in
1841-1842 was an important defense of the harbor."
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