This building is improperly called "Fort Vauban" by tourist brochures, while the construction of the original citadel is much earlier than the modification carried out by Vauban.
The mouth of the Charente was a strategic site at all times. In Roman times the site of Fouras was on an island and around 58 BC a Roman castrum called “Caesar’s Castle” occupied the site.
In the 11th century, the châtellenie of Fouras legally returned to the Rochefort family who obtained the rights to exercise high, medium and low justice, and to tax (toll) boats using the river.
In 1305, Philippe le Bel bought Fouras and attached him to the crown, then again conceded this stronghold which would change lord several times, until Jehan II de Brosse, lord of L'Aigle in 1449 (1454?), Who had built the keep from 1480 to 1490. It was the end of the Hundred Years War.
During the wars of religion, the strategic position of Fouras allowed him to escape the destruction ordered by Louis XIII for all the strongholds after the capture of La Rochelle. He made it a royal fortress.
During the Dutch War (1672 to 1678), Fouras protected the arsenal of Rochefort built in 1666 by defending the mouth of the Charente.
From 1689 to 1693, under the supervision of Vauban, François Ferry, engineer of Louis XIV, transformed the old feudal residence into a "fort by the sea". It thickens the walls of the keep and creates, 36 m above the sea, a firing platform for 9 cannons. He reinforced the medieval rampart and gained the sea by building a false braie intended to carry the bulk of the cannons.
In 1705 Ferry had barracks built on the current parking lot. It housed the garrison and served as a rampart for the keep.
The fort will be equipped with 50 cannons spread over 3 levels of fire: the false braie, the courtyard and the top of the keep, and will have a garrison of 300 to 600 men. Its shape is reminiscent of a warship: the horseshoe structure at the front (bow), the high medieval courtyard (upper deck), the keep (mast) and the ramparts (bridge).
Fort de Fouras did not fire a shot, even during the two British attacks on the harbor, in 1757 and 1809. It would remain in service until the arsenal was closed in 1927.
The fort and the citadel were classified as a historical monument on March 13, 1987