The San Carlos de la Barra fort is one of a number of coastal fortifications which the Spanish built in Venezuela in colonial times.
In 1666 the French pirate Jean David Nau El Olonés with a fleet of 8 ships and 650 men entered from the Gulf of Venezuela into the mouth of Lake Maracaibo where the Castle of San Carlos was located armed with 16 guns and attacked the fort.
Upon learning of the futility of escaping Lake Maracaibo by crossing the castle, Morgan tried to negotiate with the Spaniards by asking a ransom for hostages from the town.
The Spanish hurriedly abandoned the fort, while some soldiers remained in the castle attempting to block access back to the sea, without success.
Morgan returned to Jamaica on May 14, 1669, under warnings from the English governor Thomas Modyford before claims of the misdeeds they committed were received in London.