After Vernon’s attack in 1741 many of the defenses had been ruined and needed repair, and the island of Tierrabomba was not an exception. In 1742 two military engineers, Juan Bautista Mac Evan and Antonio Arévalo, emblematic agents in the history of the city’s fortifications, arrived in Cartagena.
Coronel Mac Evan was a protagonist, together with the governor, Ignacio Sala, who arrived in 1749 and was also a military engineer, in the dispute over the defensive strategy of the Bocachica passage. The governor proposed the construction of a basic fort with only one battery on a hill with its back to Bocachica to defend the island from a land incursion, while Mac Evan preferred a location near San Luis and a fortress that was clearly a maritime defense. This was the proposal that convinced the Crown in 1752.
With Sala no longer occupying his position, and Mac Evan deceased, it was Captain Antonio de Arévalo who, on March 12, 1753 began the work, adding the modifications proposed by the newly appointed engineer and director, Lorenzo de Solís. The new fort, named San Fernando in honor of the reigning monarch, Fernando VI, concluded its first stage of construction in 1759.
It is shaped like a horseshoe facing the sea with two large bulwarks on the northern side facing land, named the King and Queen. San Fernando was given an esplanade that ended in the empty space of a splendid moat twenty feet high without a covered walkway, nine bomb-proof vaults, and a hornwork facing the countryside.
The King’s bulwark, on the west, faces the sea and is the most complete. It has thirteen cannons, a cistern, a covered walkway and a sentry-box. The Queen’s bulwark, somewhat smaller, defends the castle from a land attack thanks to its eight cannons; it ends with a sentry-box and a cistern, just like the King’s.
Because of the ease of a land attack, in 1760 a series of improvements developed by the engineer Arévalo were carried out: the vaults, the warehouses, the batteries of Santiago and San Francisco Regis were finished, as well as a complex of galleries, countermines and small mines that allowed for the production of controlled explosions in case of a land attack.
At the beginning of the XIX century, during the process of liberation from the Spanish Crown, San Fernando was a prison to some of the leaders of the Independence. The subsequent pacification as well as advances in armaments, left the fortress in a state of abandon.
After the repairs carried out by the Society for Public Improvements, San Fernando de Bocachica stands majestically at the entrance to the bay. Its privileged location and splendid construction make the view of San Fernando one of the obligatory fortresses of Cartagena.