Every Medieval Enthusiasts Dream: Dukes Castle Unearthed in Brittany

INRAP

In an exciting revelation for both history buffs and archaeology enthusiasts, the long-lost Château de l’Hermine in Vannes has been unearthed, offering a glimpse into the grandeur of medieval Brittany.

An Inrap team – commissioned by the City of Vannes – has just unearthed the remains of the Château de l’Hermine, built by the Duke of Brittany Jean IV from the 1380s. The research revealed the ducal dwelling and its ornamented facade, different rooms as well as circulation spaces including several staircases. The whole allows us to sketch a first plan of this building.

Commissioned by the State services (Drac Bretagne), the operation was carried out as part of preventive archaeology, ahead of the construction of the future Museum of Fine Arts of the City of Vannes.

The first phase took place between February and April 2023, in the cellars and in the current courtyard of the Lagorce Hotel, a private mansion built at the end of the 18th century on the ruins of the medieval castle. A second phase of excavation, carried out in the fall of 2023, made it possible to expand the excavation area and complete the observations in the courtyard of the current building.

A Building Constructed in the Form of a “Porch Dwelling”

An archaeological diagnosis carried out by Inrap in 2021 demonstrated that masonry of the medieval building remained under the footprint of the mansion, without the full extent being perceived.

Under a thick embankment (2.5 to 4 meters/8 to13 feet), archaeologists unexpectedly uncovered the ground floor of an imposing building of which they excavated to over a meter in depth, and which corresponds to the ducal residence.

Site being stripped, view towards the southwest. (© Emmanuelle Collado/ Inrap)

A central passage connects the north door, built in the city side facade, to another door framed by two large towers sitting on the city wall and identified on old plans. These overlook the exterior moat.

The whole building has a “porch-house” plan similar to that of the Château de Suscinio (Morbihan), the pleasure residence of the Dukes of Brittany, a model that spread from the second half of the 14th century. The residential space develops partly above the passage into the towers, an architecture which combines residential functions (chimneys, latrines, etc.) and defensive functions.

The excavation gradually revealed the plan of the ground floor of the ducal dwelling, 42 meters (138ft) long and 17 meters (56 ft) wide, with exceptionally thick walls, reaching 5.60 meters (18.5 ft).

This is directly bordered by a moat, and flanked to the east by what is described as a “square tower”.

In the thickness of the facade walls, archaeologists observed a certain number of architectural structures. They uncovered several staircases, including a remarkably preserved ceremonial staircase, presenting a decorated core and three steps, but also a cushioned window (a bench in the embrasure).

Remains of the first steps of the main spiral staircase. (Rozenn Battais/Inrap)

Moat, Latrines, and Mill: a Castle Surrounded by Water

In the thickness of the masonry, at each end of the house, archaeologists have also uncovered a set of latrines and drainage pipes relating to the upper levels. The castle must therefore have had three or even four floors. The pipes lead to pits, one of which is corbelled above the interior moat.

Latrine space set up in the west gable of the house. (Rozenn Battais/Inrap)

The excavation also revealed the presence of a mill integrated – in a very original way – into the residential space, in a room of the “square tower” extending the east gable of the house. The elements of the mill have disappeared but the place where the wheel was inserted into the masonry could be located.

Staircase leading to the technical room of the mill, to the east of the house. (Rozenn Battais/ Inrap)

A canal passing under the building carried water from the Marle river to power the wheel. The latter drove the spinning wheel then the lantern, the location of which archaeologists have found. Metal staples and ties reinforced the structure.

The evacuation of water towards the moat, downstream of the wheel, was done through an opening made in the facade, the grille of which has been preserved.

Grate closing the outlet of the canal supplying the mill wheel (east). (Rozenn Battais/ Inrap)

This façade, which forms the scarp of the moat and was filled with water thanks to the canal, is laid out as a glacis (gentle slope) before plunging vertically over a total height of 4.5 meters (15 ft) to the bottom of the moat.

Moat and Bridge

Facing the entrance to the castle, the pier of a bridge has been partly cleared. This masonry massif measuring almost 5 meters (16.5 ft) on each side is made up of a central passage bordered by two jambs rising more than 2 meters (6.5 ft) high. A wooden bridge connected it to the entrance to the castle. This essential development allowed access to the city.

Clearing and cleaning the bridge pier. (Emmanuelle Collado/ Inrap)

Architectural Coherence and Prestige

The uniformity of the materials used for the construction of the castle and the standardization of the modules show a mastery of site management throughout the operational chain, from the extraction of the stone to its implementation.

Around a hundred marks of workers intended for the organization of the site were discovered on the stones: they reflect this coherent and controlled architectural program. The facade of the house has a molded strip around its entire perimeter which underlines the flamboyancy of the building, as does the detail of the decorations found on the jambs of the openings and even on the stairs.

The construction of the building took place in a single phase, which demonstrates the importance of the financial and human resources used. The remains indicate that Duke Jean IV knew how to surround himself with the best engineers and craftsmen of the time.

Left; Detail of the prismatic base of the entrance gate jamb. Right; Lapidary marks on the external facing of the house. (Rozenn Battais/ Inrap)

Crockery, Coins, Jewelry, and Wooden Artifacts

Latrines and drainage pipes were searched manually. They delivered numerous objects linked to the daily life of the castle: coins, jewelry, cooking utensils (pots, frying pans, frying pans, etc.) dating from the 15th  ^/ 16th centuries, but also several wooden elements (bowls, fragments of barrels…) preserved thanks to the humidity of the environment.

In addition, archaeologists carried out a deep survey in the moat. From this very humid material, they extracted a rich collection, in which everyday objects (pins, clothing or shoe buckles, slabs covered with graffiti, etc.) rub shoulders with other objects belonging to a wealthy environment (metal dishes, keys and padlocks for furniture or boxes, etc.).

Wooden architectural elements have also been found, such as remains of the mill or the access bridge to the castle.

A selection of the huge array of medieval artifacts the excavations yielded. (Emmanuelle Collado/ Inrap)

A Duke’s Castle Fallen Into Oblivion

In 1365, Duke Jean IV signed the Treaty of Guérande putting an end to more than 20 years of conflict opposing the Penthièvre family to the supporters of de Montfort, and inherited the Duchy of Brittany. In 1381, he undertook the construction of fortresses throughout the duchy in order to assert his power.

In Vannes, the construction of the Château de l’Hermine, which became one of the strongholds of the duchy, was part of the southward expansion of the city ramparts. Carried out in a marshy area, close to the foreshore, subject to tidal flow and therefore probably little developed until then, the work undertaken is part of a vast urbanization program which doubled the surface area of ​​the city.

Known to be one of the favorite residences of Duke Jean IV, the Château de l’Hermine was used intensively for barely a hundred years. Abandoned in favor of that of Nantes by François II in the 1470s, it was definitively abandoned in the 17th  ^/ 18th centuries.

Almost absent from the archives, the building only appears in ruins on plans from the 17th century. Several authors have attempted to reconstruct the plan, but their proposals are today usurped by these archaeological discoveries.

Top image: Archaeologists in Brittany unearthed the ruins of an elaborate medieval castle and moat built in the 1380s. Source: Emmanuelle Collado/ Inrap

This is an edited translation of a the press release by INRAP, titled, “IN VANNES, THE CHÂTEAU DE L’HERMINE RESURFACES (MORBIHAN)” with an introduction by Ancient Origins editor. Available at: