Why Build the Castillo?

Although St. Augustine was founded in 1565, nearly a hundred years previous to the building of the Castillo de San Marcos, the location was guarded with wooden forts that could be easily burned or damaged by the rapacious Florida weather. Nine such fortifications were built over the years, and all were destroyed in hurricanes, burned by attackers, or simply rotted out of neglect. However, in the middle of the seventeenth century, there were two events that alarmed the Spanish court and instigated their investment in the location: the attack of Robert Searles, and the founding of Charleston.

Though Sir Francis Drake had attacked and burnt a preceding fort, when the pirate Robert Searles attacked in 1668 he did not destroy the standing fort. This led to suspicions that he might intend to return to the subdued town and convert it, and the fort, into a stronghold of piracy. Such an encampment would be used as a base for attacking Spanish treasure ships sailing from the Caribbean. The crown needed another, stronger, method of protecting against his suspected future attack.

Compounding matters, in 1670 the British founded Charleston, on the coast of the future South Carolina. Jamestown and Plymouth had been founded in the somewhat distant past but as each was reasonably far away they did not pose significant threats; New York and Maryland did not create a significant problem either. However, Charleston was only two days' sail from St. Augustine and thus posed an imminent threat from England, the constant rival of Spain. Stronger fortifications had to be built in preparation for any aggression from the British, as a wooden fort did little to protect the town.

Thus in 1672, construction began.