Hôtel de la Guerre

The Hôtel de la Guerre (literally the 'Hotel of the War') also known as Carnot Barracks is the name of a building located at 3, Rue de l'Indépendance-Américaine in Versailles, built near the Palace of Versailles. The building was built in 1760 by Jean-Baptiste Berthier, father to the later famed Marshal Louis-Alexandre Berthier, to bring together the different war offices into one central location (until then, they had been dispersed in Paris, notably at the Bastille and Hôtel de Ville). The building was one of the first buildings built in France which was designed to be 'fire proof' and 'limited the risks of a fire'. The building currently houses the Central Directorate of the Defence Infrastructure Service, part of the French Army.

The building's massive entrance was classified as a historical monument on 1 September 1922, followed by the façade on the street side and roof, classified on 16 September 1929.

History
During the height of the Seven Years' War, the Department of War was massively expanded and in need of a building were the staff could congregate together. The head of the Topographic Engineers, Jean-Baptiste Berthier, sent by the Secretary of State for War Charles Louis Auguste Fouquet, Duc de Belle-Isle, to ask Louis XV approve the construction of a building near the Palace of Versailles, which would be able to "bring together the scattered nine elements of the Army in one place so that the ministers do not need to continue their incessant round trips and wasted time between Paris and Versailles". Berthier met with the King and told him that he would be able to build a building large enough to house all these services and their archives for less than 150,000 livres. Berthier put forward that in addition to supporting the economy, the building would prevent the risk of fire by using the so-called flat vault construction (also called Saracen or Roussillon vaults). These vaults were already used in the south of France but they were introduced for the first time in the north of the country for the construction of the stables of the Château de Bizy in Normandy, owned by the Duc de Belle-Isle. This technique was however known, having even already been the subject of few publications. Work of the Count of Espie, Manière de rendering all kinds of buildings incombustible, or treatise on the construction of vaults made with bricks and plaster, Paris, Duchesne, 1754. The architect Jean-François Blondel also speaks about it and calls them the "Roussillon vaults". The architect of Prince Palatine, Pierre Patte published in 1769 Memoirs on the most important objects of architecture even evoking the work of Berthier. We can read there:

"For a long time it has been said with reason that it would be desirable to ban wood from the construction of buildings in order to protect the lives and fortunes of citizens from fires. What havoc do they not cause! Indeed, without going back to too distant times, one hundred years ago that almost the whole city of London was reduced to ashes (...) In vain have one made in all the countries the best regulations relative to fire. . Fires are still more or less equally frequent and all that has been done is to make the aid a little quicker. So in the construction of a new city one can only hope to prevent such accidents by cutting the evil by its root, that is to say by making sure to do without structural timber for the building of houses. (.. .) All kinds of reasons must therefore be involved in reforming the food of fires; and this project does not offer any obstacle which could prevent it from being carried out. Instead of half-timbered walls, brick walls can be substituted on all occasions; instead of joist floors, it is no less possible to build flat brick vaults, either in the manner practiced at the War and Foreign Affairs offices in Versailles, or following the method operated in the backyards of the castle de Bisy, near Vernon in Normandy, or finally by taking as a model the procedures used for their execution in Lyon and in Roussillon (...) " Instead of half-timbered walls, brick walls can be substituted on all occasions; instead of joist floors, it is no less possible to build flat brick vaults, either in the manner practiced at the War and Foreign Affairs offices in Versailles, or following the method operated in the backyards of the castle de Bisy, near Vernon in Normandy, or finally by taking as a model the procedures used for their execution in Lyon and in Roussillon (...) " Instead of half-timbered walls, brick walls can be substituted on all occasions; instead of joist floors, it is no less possible to build flat brick vaults, either in the manner practiced at the War and Foreign Affairs offices in Versailles, or following the method operated in the backyards of the castle de Bisy, near Vernon in Normandy, or finally by taking as a model the procedures used for their execution in Lyon and in Roussillon (...) "

It is believed that the massive fire at the Great Stables of Versailles on 13 September 1751 was caused during the fireworks display to celebrate the birth of Louis, Duke of Burgundy. As a result of the fire, Berthier used this example of the fire to work on the building in the new style, which was late expanded to all buildings relating to the armed forces.

The King granted him land, originally intended to serve as common for the Dauphine and located at the corner of the streets of the Surintendance (current street of Independence-Américaine) and Saint-Julien. Former royal vegetable garden under Louis XIII and at the beginning of the reign of Louis XIV, this land was then abandoned in favour of a new vegetable garden and left fallow in the middle of the extension of the castle's service buildings.

Begun in July 1759, construction was completed a year and a half later. Wood with the exception of a few panelled walls was excluded. The vaults of the ceilings were made of bricks bound by plaster, the floor was made of terracotta tiles, all resting on thick walls with a brick core.

In 1761, the Duke of Choiseul, who had become Secretary of State for War on the death of Marshal de Belle-Isle, had the Hotel for Foreign Affairs and the Archives of the Navy (Hôtel des Affaires Étrangères et de la Marine) built next to it, built using the same technique.

On 26 June 1762, King Louis XV, accompanied by the Dauphin came to visit the building. Berthier to demonstrate its safety made an experiment by setting fire to a pile of wood and straw placed in one of the rooms. This did not spread to neighbouring rooms.

During the Revolution, the Ministry of War moved to Paris and the building was temporarily occupied by the services of the new department of Seine-et-Oise which later did serious damage there. In 1798, it served as an extension to the arms factory installed in the neighbouring Grand Commune. The army would then take possession of it with the installation of nearly 500 infantry troops, then in 1884, the installation of a new School of Artillery, Engineering and Train, which in 1912, will become the Military Engineering Application School. During the Nazi occupation of France a police academy was set up there and, shortly after the war, a preparation centre for the grandes écoles. In 1946, the higher technical school of engineering moved there, the previous engineering school having left for Angers. In 1995, the two schools merged into a higher engineering and application school located in Angers. The building is now occupied by the central directorate of the Defence Infrastructure Service (former Central Engineering Directorate).

Original items
There is not much left of the original décor of the Hôtel de la Guerre today, with the exception of Diane's salon. On the vault, paintings on stucco illustrate the reversal of the alliances of 1756. On the walls are hung a painting representing King Louis XV on horseback giving his orders during the Flanders War in 1745, a work by Charles Cozette and 6 canvases by Pierre Lenfant, painted between 1757 and 1771. Commissioned by Louis XV, they represent the War of the Austrian Succession.

The exterior gate still exists. It is surmounted by a royal crown on a sun, framed by war trophies. Reliefs carved on the pilasters represent cornucopias from which officers' patents and Saint-Louis crosses emerge. We also see plans of fortresses and weapons.