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"Simeon de Garengeau, the fortifier of the Castle of the Roche Goyon at castle La Latte."

Who was Siméon De Garengeau ?

Siméon Garengeau ©château de la Roche Goyon

Siméon Garengeau: The Military Engineer who Defended Saint-Malo

Siméon Garangeau or Garengeau, born in Paris in 1647 and passing away on August 25, 1741, in Saint-Malo at the age of 94, was a remarkable figure of his time in France. A renowned military engineer and architect, he left an indelible mark on the defense of the French coasts and the design of religious monuments. His life and work are worthy of a deeper exploration.

Youth and Education

Siméon Garangeau was the only son of François Garangeau, a master carpenter, and Marie Dubois. After losing his father in 1698, he displayed exceptional generosity by relinquishing his inheritance in favor of his five sisters, three of whom were married and two were nuns in Saint-Cloud. This decision reflects his devotion to his family and his selfless character.

Plan du château de la Roche Goyon non daté, non signé

Military Career and Transition to Architecture

His military career began as a volunteer during the siege of Maastricht in 1673. He then rose through the ranks to become the captain of the Champagne regiment. However, an injury forced him to leave active service. Fortunately, his skills in geometric drawing, inherited from his father, led him towards the field of arts.

Elévation du fort de La latte, fait à Saint-Malo par Garangeau le 13 décembre 1697
élévation du château de la latte ou Château de la Roche Goyon

After traveling to Italy and England to refine his art, he became an architect in Paris in 1677. One year later, at the age of 31, he was appointed as the controller of the buildings of Versailles and Fontainebleau, as well as the King's engineer, during the reign of Louis XIV. This transition to architecture would become the turning point in his career.

Plan de l'élévation de la face du château de la Roche Goyon par Siméon Garengeau

Major Achievements

Siméon Garengeau oversaw numerous significant projects throughout his life. Among his most notable achievements were :

1. Saint-Louis Church in Brest : During his service in Brest, he designed this church, a testament to his architectural talent.

2. Fortifications of Saint-Malo : He was appointed chief engineer and director of the fortifications of Saint-Malo in 1691. His defensive works successfully repelled two Anglo-Dutch maritime attacks in 1693 and 1695.

3. Urban Developments : He supervised the expansion of Saint-Malo and Saint-Servan, as well as the canalization of the Couesnon River and the marshes of Dol.

4. Religious Monuments : Garangeau designed the churches of Saint-Servan, Cancale, and the Saint-Sauveur Church in Saint-Malo.

5. Castles and Forts : He worked on several castles, forts, and coastal watchtowers, including Fort de l'Île Harbour, Fort National, the redevelopment of Castle of the Roche Goyon, Fort du Petit Bé, Fort du Grand Bé, Fort de la Conchée, Fort de l'Île aux Moines, Château du Taureau, and Fort de l'Arboulé.

Couverture du livre "Le château de la Roche Goyon dit Fort La Latte" avec le plan de Siméon Garengeau

Despite the fact that his defensive works were not fully completed, they nevertheless played a crucial role in successfully repelling two Anglo-Dutch maritime attacks on Saint-Malo. The first attack occurred from November 23 to November 30, 1693, and the second from July 14 to July 18, 1695. In recognition of his exceptional engineering skills, in 1708, he was granted an annual pension of 3,800 livres, which was increased to 4,000 livres in 1717.

Un Plan d'un fort proposé par Siméon Garengeau sur la grande Isle du Rimen Seize dans la Radde de Cancale

Plan du fort propozé sur la grande isle du Rimen scize dans la radde de Cancale... 1704 - BNF - [Division 2 du portefeuille 44 du Service hydrographique de la marine consacrée à la baie de Cancale] ; 06 D

End of Life

Garengeau died at his residence on the 2nd floor of Saint-Vincent Street in Saint-Malo on August 25, 1741, at the age of 94 [PETOUT P., "Engineer Garangeau in Saint-Malo (1689-1741)," Annales de la Société d'Histoire et d'Archéologie de Saint-Malo, 1989, p. 199.].

In his death certificate, he is referred to as "Squire Siméon de Garengeau, Knight of Saint-Louis, Captain in the Champagne regiment, director of the fortifications of Upper Brittany."

He had neither a wife nor descendants.

signature de Siméon Garengeau

Signature de Siméon Garengeau, ingénieur du roi, le 15 juillet 1696 à Saint-Malo. Archives Nationales, D-2-22, pièce 29.


Siméon Garengeau left a lasting legacy in the architectural and military landscape of 17th-century France. His dedication to his family and his nation, as well as his remarkable achievements as an architect and military engineer, make him an indispensable figure of his time. His contribution to the defense of Saint-Malo against enemy attacks remains one of the highlights of his career, underscoring his commitment to the security of his country.

Today, his work endures through the monuments and fortifications he designed, silent witnesses to the ingenuity and dedication of a man who made his mark on his era.

 Plan du fort La Latte, fait à Saint-Malo par Garangeau le 4 novembre 1691
Plan du château fort La Latte ou château de la Roche Goyon, fait à Saint-Malo par Garangeau le 4 novembre 1691

Siméon Garengeau's name is often overshadowed by that of Vauban in the history of military architecture. However, Garengeau deserves recognition and celebration for his significant contribution to this crucial art.

During this era (17th - 18th century), marked by constant conflicts and the need for fortifications, Siméon Garengeau emerged as a brilliant mind in the field of military architecture in France. He was a contemporary of Sébastien Le Prestre de Vauban, a much more famous name, thanks to whom the term "Vauban style" is now widely recognized.

However, it would be unfair to overlook Garengeau's remarkable work. Indeed, he played an essential role in the design and construction of numerous fortifications, thereby contributing to the defense of the Kingdom of France. His achievements are sometimes considered ahead of his time, employing innovative ideas to strengthen fortresses and citadels.

History should remember Siméon Garengeau not only as a pupil of Vauban but also as a talented military architect in his own right. His work contributed to the security of France at a time when threats were constant, and he deserves a legitimate place in the annals of defensive architecture. It is time for his name to be remembered and honored alongside that of Vauban for his invaluable contribution to the history of military architecture.

To this day, no portrait, painting, or other visual representation of Siméon Garengeau has been discovered, leaving his personal image in the shadow of history.

The Vauban Lighthouse by Siméon Garengeau

Phare Vauban au Cap Fréhel en Plévenon (siméon Garengeau)

"The Cap Fréhel Lighthouse. 1887 - ©Archives Départementales des Côtes d'Armor, Supplementary Sheet 561, Height of 62 cm / Width of 83.5 cm / Watercolor drawing depicting development plans with general views of the Cap Fréhel lighthouse / Sheet extracted from an atlas of 22 sheets created by the subdivision of lighthouses and

beacons from Lézardrieux to the end of the 19th century."

The Vauban Lighthouse by Siméon Garengeau at Plévenon, on the tip of Cap Fréhel, is more than just a navigational structure. Erected between 1701 and 1702 on the orders of Louis XIV and Vauban, and designed by the King's engineer, Siméon Garangeau (1647-1741), it also symbolizes the powerful combination of military engineering and architecture. Its primary purpose was to enhance coastal defense and serve as a warning against potential attacks by the English fleet.

Siméon Garangeau, already renowned for his work on the ramparts of Saint-Malo and numerous coastal forts (as mentioned earlier), rigorously applied the methods of the Department of Land and Sea Fortifications to the construction of this lighthouse. He based it on the model of the "fire tower," which served as both a watchtower and a lighthouse, devised by Vauban for the most strategic points along the Breton coast.

This imposing round tower, complete with a spiral staircase, housed stores and the keeper's quarters on three levels. The ground floor was used for storing coal, the upper level served as a guardroom during wartime, while the keeper resided at the top of the tower, responsible for keeping the beacon lit. The fire, fueled by wood and coal, burned openly in an iron brazier located at the top of the structure.

In the 18th and early 19th centuries, the lighthouse played a major strategic role in navigation, as evidenced by its presence as "Fanal" on a map illustrating an English landing attempt in the Bay of Saint-Malo. Cap Fréhel, ideally situated between the Bay of Saint-Brieuc and the harbor of Saint-Malo, served as a crucial landmark for sailors wishing to dock in the major trading port of Saint-Malo, whose access was from west to east, through the reefs.

However, the supply of coal required to maintain the light soon became problematic. In 1774, an innovative solution was implemented, inspired by street lighting lanterns. A glass lantern housed sixty reflector lamps fueled by fish oil or other sources. Each lamp had a metallic reflector, arranged in three superimposed rows, to illuminate three-quarters of the circumference facing the sea. However, despite attempts to mix different oils, results were often hampered by smoke on the walls, making this method imperfect.

Starting in 1793, the State took over all operating expenses, ensuring maintenance through a private contractor who provided higher-quality rapeseed oil, employed two keepers, and covered the necessary repairs to the buildings and lighting apparatus.

In 1821, a significant technological advancement appeared with a clockwork mechanism to rotate the lighthouse. This resulted in a long light flash every 135 seconds, increasing the luminous intensity to 21 miles offshore. This improvement was made possible by adding eight large parabolic reflectors with a diameter of 60 cm.

During World War II, the Germans destroyed the 19th-century lighthouse, and the Lighthouse Service took the initiative to install a temporary light on the Vauban tower by Siméon Garengeau, which had miraculously survived the ravages of war, while the local people built a new, more modern lighthouse.

Siméon Garengeau's Vauban Lighthouse in Plévenon remained an essential pillar for navigation in the region for a long time, combining military engineering with maritime safety.

Plan d'un projet de phare pour l'ile de Batz de formes et de conception similaire à celui que l'on retrouve au Cap Fréhel, de Siméon Garengeau datant du 9 janvier 1705, les coupes horizontales sont sur des volets collés avec les différents niveaux

"Elevation of the proposed tower to be built on the island of Bas, about sixteen and a half miles out to sea in front of Roscoff, to serve as a beacon for the safety of navigation." - Archives départementales d'Ille-et-Vilaine

A project for the Batz lighthouse, similar to that of Cap Fréhel, and the beautifully restored Stiff lighthouse on the island of Ouessant."

Source :

Here is the list of individuals mentioned in this chronicle :

1. Siméon Garengeau (or Garangeau) - Renowned military engineer and architect, the main protagonist of the text.

2. François Garangeau - Father of Siméon Garengeau, a master carpenter.

3. Marie Dubois - Mother of Siméon Garengeau.

4. Five sisters of Siméon Garengeau, including three married and two nuns at Saint-Cloud.

5. Louis XIV - King of France during whose reign Siméon Garangeau worked as the king's engineer.

6. Vauban - Military engineer and architect under Louis XIV.

These individuals are primarily related to the biography and career of Siméon Garengeau, highlighting his significant impact on military architecture and fortifications in France.

In addition to the previously mentioned individuals, here are the entities and places mentioned in the text about Siméon Garengeau :

1. Paris - Birthplace of Siméon Garengeau.

2. Saint-Malo - City where Siméon Garengeau passed away and where he made significant contributions to fortifications.

3. Siege of Maastricht (1673) - Military event in which Siméon Garengeau participated as a volunteer.

4. Champagne Regiment - Military unit in which Siméon Garengeau served as a captain.

5. Italy and England - Countries visited by Siméon Garengeau to refine his skills.

6. Versailles and Fontainebleau - Locations where Siméon Garengeau was appointed as the controller of buildings.

7. Saint-Louis Church in Brest - One of the architectural achievements of Siméon Garengeau.

8. Fortifications of Saint-Malo - Defensive projects led by Siméon Garengeau.

9. Saint-Servan - Site of urban developments supervised by Siméon Garengeau.

10. Cancale - Location where Siméon Garengeau worked on a church.

11. Saint-Sauveur Church in Saint-Malo - Another architectural achievement of Garengeau.

12. Fort of Harbour Island, National Fort, Roche Goyon Castle, Petit Bé Fort, Grand Bé Fort, Conchée Fort, Île aux Moines Fort, Taureau Castle, and Arboulé Fort - Forts and castles worked on by Siméon Garengeau.

13. Couesnon and Dol Marshes - Sites of development projects overseen by Garengeau.

14. Cap Fréhel Lighthouse - Construction designed by Siméon Garengeau.

15. Batz Lighthouse and Stiff Lighthouse on the island of Ouessant - Other lighthouse projects similar to that of Cap Fréhel.

These locations and entities are significant for understanding the scope of Siméon Garengeau's work and his impact on military and civilian architecture in 17th-century France.


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