Fortifications of Paris in the 19th and 20th centuries

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

They were built in two stages:

From a military point of view, Paris is a fortified camp situated in a basin. During the 19th century, both Prussian invasions (1814–15 and 1870) saw the bombardment of Paris from the surrounding heights. Fortifications were extended outwards after each invasion as the range of artillery continued to develop, in order to deny the use of the heights to the enemy.

1670 The king demolishes the walls of Charles V and Louis XIII. Paris becomes an open city and remains so for two centuries.

1689 Vauban 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.

1784 The king orders the construction of the Farmers General Wall, built not as a fortification, but as a means of taxation.

1814-1815 Paris is occupied twice at the end of the reign of Napoleon I.

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 for Paris envisages:

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

...
Wikipedia