Three and a half centuries ago Cartagena de Indias was renowned as the richest trading center and most beautiful city on the Spanish Main. It was the principal emporium for merchandise sent from Spain to its South American colonies and the shipping point for gold, silver, emeralds, and pearls mined in Colombia and Venezuela. Between 1544 and 1741 Spain’s enemies sacked the town five times.

Built on a narrow, low strip of land between the open Caribbean Sea to the north and a huge bay behind, Cartagena was hard to defend. The marshy soil made poor footing for the heavy stone fortifications required in the tropics, and in any case there was no stone to build them with. The only harbor entrance was miles to the south.

Lack of landing beaches, heavy surf, and shallow water that kept bombarding ships at a distance combined to make the direct northern approach quite secure. The back door, however, presented problems beyond the capacities of seventeenth-century weapons and tactics. Once inside the bay an attacker could easily close in from the south.

Over two centuries, as requirements and military tactics changed, Cartagena’s defenses expanded and contracted. From a small log stockade on the harbor side of the town and a small gun battery at Boca Grande the system grew into an elaborate series of six stone forts around the bay, two guarding the entrance, and a seven-mile-long seawall around the city bristling with more than two hundred cannons. The wall alone took more than two centuries to complete.

The core of the system was the citadel of San Felipe de Barajas, a hill slightly southeast of the city in the eighteenth century but now well within it. Initially only a small eight-gun redoubt some 135 feet above sea level, it gradually grew into a massive stone fortress whose ramparts could sweep the city with seventy big guns.

San Felipe was—and still is—an amazing network of tunnels and passageways connecting storage vaults, housing, magazines, and batteries. In the sheer mass of its battlements and in the ingenuity of its water and ventilation systems, the fortress is ranked by engineers as equal, if not superior, to Gibraltar. Today it is a major tourist attraction.

Unfortunately the individual forts were too far apart to support one another. While they were formidable obstacles to direct attack, they could be cut off by landing parties and reduced one after the other. The gateway batteries, especially, never displayed much enthusiasm for a last-ditch defense.

In 1741 the British admiral Edward Vernon toppled the inner forts in turn but got his nose bloodied on San Felipe. Thanks to the stubborn leadership of Don Bias de Lezo, a one-eyed, one-armed, one-legged old fire-eater, the effort to take Cartagena failed. Don Bias caught one too many during the siege and died of his wound, but the campaign gave the name to one of the United States’s most revered historical shrines: George