Cumberland's Siege and Capture of San Juan (1598)

On June 15, 1598, just three years after Drake's failed assault, George Clifford, the 3rd Earl of Cumberland, arrived at Puerto Rico with 20 ships and approximately 1,700 soldiers. Learning from Drake's mistake of attacking the heavily fortified harbor directly, Cumberland landed his forces at the Boquerón inlet east of San Juan and marched overland to attack El Morro from its less defended landward side.

The strategy worked. After fierce fighting, Cumberland's forces overwhelmed the Spanish garrison and captured Castillo San Felipe del Morro—making it the only time in the fortress's history that a foreign power successfully took it. The Spanish defenders retreated into the interior of the island, and Cumberland occupied the city of San Juan.

However, victory proved hollow. A devastating epidemic of dysentery swept through the English forces, killing hundreds of soldiers. The disease, likely contracted from contaminated water supplies or tropical conditions the English were unprepared for, proved more lethal than Spanish cannon fire. After 65 days of occupation, Cumberland was forced to withdraw, but not before his soldiers systematically sacked and burned much of San Juan, carrying away valuables including church bells, sugar, hides, and ginger.

The siege demonstrated both the vulnerability and the ultimate resilience of San Juan's position. While a determined force could capture the city, holding it against disease, supply problems, and the hostile tropical environment proved impossible for European invaders. Spain subsequently accelerated the fortification of San Juan, adding new walls, bastions, and the massive San Cristóbal fortress to prevent future landward attacks. Cumberland's brief occupation became the cautionary tale that shaped Puerto Rico's military architecture for the next two centuries.