Fortifications of Paris in the 19th and 20th centuries

The fortifications of Paris in the 19th and 20th centuries comprise:

The Thiers Wall
Thiers wall
The Thiers wall was the last of the defensive walls of Paris. It was an enclosure constructed between 1841 and 1844 under a law enacted by the government of the French prime minister, Adolphe Thiers. It covered , along the 'boulevards des Maréchaux' of today...

, surrounding the city of Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

, and farther from the city,
The detached forts and their complementary fieldworks.

They were built in two stages:

1840-1845: the Thiers Wall and the first ring of forts, about five kilometers from the city;
1874-1885: the second ring of forts, about twenty kilometers from the city.

General context

From a military point of view, Paris is a fortified camp situated in a basin. During the 19th century, each Prussia

Prussia

Prussia was a German kingdom and historic state originating out of the Duchy of Prussia and the Margraviate of Brandenburg. For centuries, the House of Hohenzollern ruled Prussia, successfully expanding its size by way of an unusually well-organized and effective army. Prussia shaped the history...

n invasion (1814–15 and 1870) saw the bombardment of Paris from the surrounding heights. Fortifications were extended outwards after each successive invasion as the range of artillery continued to develop, in order to deny the use of the heights to the enemy.

Louis XIV

1670 The king demolishes the walls of Charles V

Wall of Charles V, Paris

The wall of Charles V, built from 1356 to 1383 is one of the city walls of Paris. It was built on the right bank of the river Seine, outside the wall of Philippe Auguste and replaced it. In the 1640s, the western part of the wall of Charles V was demolished and replaced by the larger Louis XIII...

and Louis XIII. Paris becomes an open city and remains so for two centuries.

1689 Vauban

Vauban

Sébastien Le Prestre, Seigneur de Vauban and later Marquis de Vauban , commonly referred to as Vauban, was a Marshal of France and the foremost military engineer of his age, famed for his skill in both designing fortifications and breaking through them...

recommends the enclosure of Paris, with the construction of a second enclosure to include the then-villages of Chaillot, Montmartre and Belleville (located on heights overlooking the city), and two citadels flanking the city to the east and west to delay an enemy's approach.

Louis XVI

The king orders the construction of the Farmers General Wall, built not as a fortification, but as a means of taxation.

First fortification program

1818 Minister of War Laurent de Gouvion-Saint-Cyr creates a commission to "present its views on the best defense system" for Paris.

1820 The commission concludes that Paris must be placed in a state of defense, but proposes no specific project.

1830 Creation of a committee to study fortification which returns to the debate and again concludes that fortification is necessary, without consensus on how this is to be done.

1833 The defense plan fo Paris envisages:

The improvement of the Farmers General Wall (a tariff barrier) to a height of six meters, two ranges of crenelations and 65 towers or bastions;
In advance of the Farmers General Wall, several delaying fortifications, along with a fortiffied line along the canal between Romainville
Romainville
Romainville is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.-History:On 24 July 1867, a part of the territory of Romainville was detached and merged with a part of the territory of Pantin and a part of the territory of Bagnolet to create the commune of...

and Saint-Denis
Saint-Denis
Saint-Denis is a commune in the northern suburbs of Paris, France. It is located from the centre of Paris. Saint-Denis is a sous-préfecture of the Seine-Saint-Denis département, being the seat of the Arrondissement of Saint-Denis....

, and a system of floodable areas around Saint-Denis;
Ground works with casemates and star-shaped forts and redoubts on the heights between Saint-Denis and Nogent-sur-Marne
Nogent-sur-Marne
Nogent-sur-Marne is a commune in the eastern suburbs of Paris, France. It is located from the centre of Paris. Nogent-sur-Marne is a sous-préfecture of the Val-de-Marne département, being the seat of the Arrondissement of Nogent-sur-Marne.-History:...

; transformation of the Château de Vincennes
Château de Vincennes
The Château de Vincennes is a massive 14th and 17th century French royal castle in the town of Vincennes, to the east of Paris, now a suburb of the metropolis.-History:...

into a mdern fort. The works, carried out by General Éléonor-Zoa Dufriche de Valazé were often stopped and were not completed. In fact, two options worked in opposition:
Option 1. A broad continuous enclosure that includes the suburbs in the defensive system, but not employing the Farmers General Wall. Valazé supports this scheme, a continuation of the plans of Vauban and François Nicolas Benoît, Baron Haxo
François Nicolas Benoît, Baron Haxo
François Nicolas Benoît, Baron Haxo was a French Army general and military engineer.-Biography:He was born at Lunéville and entered the Engineers in 1793....

.
Option 2. The arrangement of the capital as a vast fortified camp, based on permanent forts occupying the principal positions while keeping a "containment shell" behind. Criticisms of this option relate to the insufficiency of the guarantee of defense: an enemy could easily penetrate between the obstacles, then engage the Farmers General fortifications.

1836 Creation of a commission on the defense of the kingdom.

1838 On July 16 a plan of defense is adopted, combining the two options in a show of unanimity.

1840 The Treaty of London excludes France. Adolphe Thiers

Adolphe Thiers

Marie Joseph Louis Adolphe Thiers was a French politician and historian. was a prime minister under King Louis-Philippe of France. Following the overthrow of the Second Empire he again came to prominence as the French leader who suppressed the revolutionary Paris Commune of 1871...

, considering that vthe new treaty includes the germ of a new invasion threat, seizes the occasion to commence the construction of the new fortifications. On September 1 General Guillaume Dode de la Brunerie

Guillaume Dode de la Brunerie

Guillaume Dode de la Brunerie was a Marshal of France. On February 12, 1812, he married the daughter of Marshal Pérignon, Agathe-Virginie.-Early life and French revolutionary wars:...

is named director of the fortification program. The appointment and work is publicly announced on September 13.

1841 Over the reservations of the General Council of the Seine, 140 million francs are appropriated for the work, allocated, including
17,970 million francs for land acquisition, 16,608 million francs for earthwork, and 83,356 million francs for masonry. The law authorizing work was promulgated by Louis-Philippe I on April 3, authorizing a continuous wall for both sides of the Seine, known as the Thiers Wall

Thiers wall

The Thiers wall was the last of the defensive walls of Paris. It was an enclosure constructed between 1841 and 1844 under a law enacted by the government of the French prime minister, Adolphe Thiers. It covered , along the 'boulevards des Maréchaux' of today...

, supported by sixteen detached forts.

1845 Work is completed.

1860. The limits of the city of Paris are extended from the Farmers General Wall to the Thiers Wall, in accordance with the reorganization of the Paris urban fabric planned and executed by Georges Eugène Haussmann.

Franco-Prussian War

July 1870 France declares war on Prussia

Prussia

, July 13.

September 1870 Napoleon III is captured at Sedan and capitulates. A republic is proclaimed and a provisional government named. The Prussians move toward Paris. The capital is transformed into a fortified camp. A portion of the Thiers Wall gates are closed, along with canals and rail line entries. Houses are demolished in the designated "zone 'non aedificandi" to clear lines of fire. The Prussians arrive on 19 September and establish a siege, which will last four months.

January 1871 On the 28th the Treaty of Versailles is signed, stipulating that all all of the forts forming the perimeter defense of Paris, together with their armaments, be handed over to the German forces. The treaty further stipulates the disarmament of the Thiers Wall.

March 1871 The German army abandons the forts on the left (south) bank of the Seine.

20 September 1871 The German army abandons the forts on the right (north) bank of the Seine.

Second program of fortification

During the 1870 war, the fortifications were relatively ineffective.

1874 On 17 July, a law inspired by the ideas of Séré de Rivières

Séré de Rivières system

The Séré de Rivières system was an ensemble of fortifications built from 1874 and first used at the beginning of the First World War along the frontiers and coasts of France...

creates new programs for defensive works in the north and east of France, including some intended for the defense of Paris.

1885. The program is completed. 196 forts, 58 smaller works and 278 batteries are in place on the borders and at strategic points within France at an estimated cost of 450 million francs for the works and 229 million francs for their armament.

The removal of the Thiers Wall

1883 On June 11 the municipal council of Paris votes to request the removal of the Thiers Wall, the property's transfer to the city and the end of restrictions on building in its vicinity.

1918 During the war the Thiers Wall proves to be ineffective in the defense of Paris, as the range of German artillery such as the Paris Gun

Paris Gun

The Paris Gun was a German long-range siege gun used to bombard Paris during World War I. It was in service from March-August 1918. When it was first employed, Parisians believed they'd been bombed by a new type of high-altitude zeppelin, as neither the sound of an airplane nor a gun could be heard...

(120 km) renders walls irrelevant.

1919 On 19 April the city purchases the property for 100 million francs from the State of France. The city must purchase or expropriate the associated grounds and must maintain the "zone non aedificandi." Work begins on the demolition of the walls.

1925-1930 The "terretoire zonier" is annexed to the city.

1930 A law is enacted to regulate the methods for compensation of the "zoniers."

Military doctrine for the employment of the forts

The doctrines for the use of the forts depend on the context of the time. During the 19th century the roads are few. Armies were obligated to move along existing lines of communication in order to maintain their provisioning without resorting to dirt roads in unfavorable seasons. Therefore, a fortification located on an important road would be able to slow or stop a large troop formation. For example the Fort de Charenton was placed to dominate Route Nationale 6

Route nationale 6

The Route nationale 6 is a trunk road in France between Paris and the frontier with Italy in the Alps.- Reclassification :The RN 6 runs parallel for a long portion of its route to the A 6 autoroute...

, the Paris-Geneva road, and Route Nationale 6

Route nationale 19

The Route nationale 19 is a trunk road in north east France. The road forms part of European route E54.-Reclassification:The RN19 has been subsequently downgraded in several sections to the RD319 and RD619.-Route:...

, the road to Belfort, as well as the Pont de Charenton on the Marne

Marne

Marne is a department in north-eastern France named after the river Marne which flows through the department. The prefecture of Marne is Châlons-en-Champagne...

and the Pont à l’Anglais on the Seine.

In wartime, the fort would fulfill several functions, in the manner of a fortified town.

The fort would provide a place of shelter for troops while passively resisting an assault by the enemy.
If the enemy ignores the fort and circumvents it, they will be subject to attack from the rear by the fort's garrison, obliging a portion of the attacking forces to remain behind as protection.
It is a point of concentration and protection for artillery
It is a point of support for friendly forces

First ring of forts

The first ring of sixteen detached forts and complementary works, constituting the first line of defense a few kilometers from Paris, and supporting the Thiers Wall encircling Paris.

The sixteen forts

The sixteen forts built around Paris between 1840 and 1845 are shown in the following table.

The order described in the first column describes the forts in order as they appear as one proceeds clockwise aound Paris (north-east-south-west). Forts are named for the communities they defended, not necessarily those in which they are located.

Order	Dir.	Name	Emplacement	Distance from the Farmers General wall	Distance from the Louvre	Other works
1	N	Fort couronne de la Briche	Saint-Denis	6900 m	9600 m
2	N	Fort de la Double-Couronne	Saint-Denis	6850 m	9600 m
3	N/E	Fort de l'Est Fort de l'Est Fort de l'Est is a military strong point designed to protect Paris. It was built between 1841 and 1843 in Saint-Denis at the direction of French prime minister Adolphe Thiers, and was part of a immense defensive belt comprising 17 detached forts and the Thiers Wall surrounding Paris...	Saint-Denis	5000 m	7900 m
4	N/E	Fort d'Aubervilliers	Aubervilliers Aubervilliers Aubervilliers is a commune in the northeastern suburbs of Paris, France. It is located from the center of Paris.-Name:In medieval times the name Aubervilliers was recorded as Alberti Villare, meaning "estate of Adalbert"...	3875 m	7250 m	Works and battery
5	E	Fort de Romainville Fort de Romainville Fort de Romainville, was built in France in the 1830s and was used as a Nazi concentration camp in World War II.- Use in WWII :...	Les Lilas Les Lilas Les Lilas is a commune in the eastern suburbs of Paris, France. It is located from the centre of Paris. It is one of the most densely populated municipalities in Europe.- History :...	3500 m	6650 m	Lunette + Courtine
6	E	Fort de Noisy	Romainville Romainville Romainville is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.-History:On 24 July 1867, a part of the territory of Romainville was detached and merged with a part of the territory of Pantin and a part of the territory of Bagnolet to create the commune of...	4800 m	8300 m	Lunette + Redoubt
7	E	Fort de Rosny	Rosny-sous-Bois Rosny-sous-Bois Rosny-sous-Bois is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.It is the seat of the national centre of road information of the national gendarmerie.- Heraldry :-Transport:...	5750 m	9800 m	Lunette
8	S/E	Fort de Nogent Fort de Nogent The Fort de Nogent or Fort de Nogent-sur-Marne is a French fortification forming part of the fortifications of Paris. Despite its name, the fort is located in Fontenay-sous-Bois; the name is derived from Nogent-sur-Marne the town the fort was planned to protect...	Fontenay-sous-Bois Fontenay-sous-Bois Fontenay-sous-Bois is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.-Name:The name Fontenay was recorded in the Middle Ages as Fontanetum, meaning "the springs", from Medieval Latin fontana .The commune was known alternatively as Fontenay-les-Bois ,...	5900 m	10300 m	Lunette
9	S/E	Fort Neuf de Vincennes Fort Neuf de Vincennes The Fort Neuf de Vincennes is a fortification built on the grounds of the Château de Vincennes, on the east side of Paris. While the old chateau had been a significant fortification in its time, by 1840 there was a need for a modern fort at that location, capable of using and defending itself...	Vincennes Vincennes Vincennes is a commune in the Val-de-Marne department in the eastern suburbs of Paris, France. It is located from the centre of Paris. It is one of the most densely populated municipalities in Europe.-History:...	2800 m	7800 m
10	S/E	Fort de Charenton Fort de Charenton Fort de Charenton is a fortification built in 1842 in the community of Maisons-Alfort, and part of the Paris defenses planned by Adolphe Thiers....	Maisons-Alfort Maisons-Alfort Maisons-Alfort is a commune in the southeastern suburbs of Paris, France. It is located from the center of Paris.Maisons-Alfort is famous as the location of the National Veterinary School of Alfort, the most renowned veterinary medical school in France...	4000 m	8400 m	Rigole
11	S	Fort d'Ivry Fort d'Ivry Fort d'Ivry was built in the Paris suburb of Ivry-sur-Seine between 1841 and 1845 as one of the forts in a ring of strong points surrounding Paris. The fort is about 1 kilometer outside the Thiers Wall, built by the same program in response to a perception that Paris was vulnerable to invasion and...	Ivry-sur-Seine Ivry-sur-Seine Ivry-sur-Seine is a commune in the Val-de-Marne department in the southeastern suburbs of Paris, France. It is located from the center of Paris....	3900 m	7300 m
12	S	Fort de Bicêtre Fort de Bicêtre The Fort de Bicêtre is a military structure built between 1841 and 1845 during the reign of Louis-Philippe during a time of tension between France and England, in the Paris suburb of Kremlin-Bicêtre. The fort is part of the Thiers Wall]] fortifications of Paris, built under a program of defensive...	Le Kremlin-Bicêtre Le Kremlin-Bicêtre Le Kremlin-Bicêtre is a commune in the southern suburbs of Paris, France. It is located from the center of Paris. It is one of the most densely populated municipalities in Europe....	2650 m	6100 m
13	S	Fort de Montrouge	Arcueil Arcueil Arcueil is a commune in the Val-de-Marne department in the southern suburbs of Paris, France. It is located from the center of Paris.-Name:The name Arcueil was recorded for the first time in 1119 as Arcoloï, and later in the 12th century as Arcoïalum, meaning "place of the arches" , in...	2900 m	5800 m
14	S	Fort de Vanves	Malakoff	3600 m	6400 m
15	S	Fort d'Issy	Issy Issy-les-Moulineaux Issy-les-Moulineaux is a commune in the southwestern suburban area of Paris, France. It is located from the centre of Paris. On 1 January 2003, Issy-les-Moulineaux became part of the Communauté d'agglomération Arc de Seine along with the other communes of Chaville, Meudon, Vanves and Ville-d'Avray...	3900 m	6850 m
16	W	Fort Mont-Valérien Fort Mont-Valérien Fort Mont-Valérien is a fortress in Suresnes a western Paris suburb, built in 1841 as part of the city's ring of modern fortifications...	Suresnes Suresnes Suresnes is a commune in the western suburbs of Paris, France. It is located from the center of Paris. The nearest communes are Neuilly-sur-Seine, Puteaux, Rueil-Malmaison, Saint-Cloud and Boulogne-Billancourt...	5250 m	9100 m

Complementary works

Order	Name	Emplacement	Date
1	Digue du Croult	Saint-Denis
2	Digue du ru de Montfort,	Saint-Denis
3	Batterie des Vertus	Aubervilliers Aubervilliers Aubervilliers is a commune in the northeastern suburbs of Paris, France. It is located from the center of Paris.-Name:In medieval times the name Aubervilliers was recorded as Alberti Villare, meaning "estate of Adalbert"...
4	Redoute de la Flache	Aubervilliers Aubervilliers Aubervilliers is a commune in the northeastern suburbs of Paris, France. It is located from the center of Paris.-Name:In medieval times the name Aubervilliers was recorded as Alberti Villare, meaning "estate of Adalbert"...
5	Batterie de Pantin	Pantin Pantin Pantin is a commune in the northeastern suburbs of Paris, France. It is located from the center of Paris. It is one of the most densely populated municipalities in Europe. Its post code is 93500.Pantin was once the site of Motobecane's operations...
6	Redoute de Montreuil
7	Redoute de la Boissière	Rosny-sous-Bois Rosny-sous-Bois Rosny-sous-Bois is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.It is the seat of the national centre of road information of the national gendarmerie.- Heraldry :-Transport:...	1831
8	Redoute de Fontenay-sous-Bois	Fontenay-sous-Bois Fontenay-sous-Bois Fontenay-sous-Bois is a commune in the eastern suburbs of Paris, France. It is located from the center of Paris.-Name:The name Fontenay was recorded in the Middle Ages as Fontanetum, meaning "the springs", from Medieval Latin fontana .The commune was known alternatively as Fontenay-les-Bois ,...
9	Redoute de Gravelle Redoute de Gravelle The redoute de Gravelle is a fort in Joinville-le-Pont, situated to the south-east of Vincennes in Paris. Built under Louis-Philippe, from 1968 it housed the École nationale de police de Paris , before becoming an illegal immigrants detention centre...	Paris Paris Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region... (bois de Vincennes)
10	Redoute de la Faisanderie
11	Batterie du Rouvray

Second ring of forts

This section includes those works completed between 1870 and 1890 as part of the Séré de Rivières fortifications