[1] This fort was built between 1852 and 1854 on modified plans by Sébastien Le Prestre de Vauban (1633–1707).

[4] A fort project had already been issued by Vauban at the end of the 17th century, but it had not been built with the exception of the southern front integrated into the defensive system of the Quélern lines.

[8] In the center of these chambers were the administrative rooms, the accommodation of the director, the guards, while the southern part has been preserved for military use.

Several hundred Communards, including the geographer Élisée Reclus (1830 –1905) and the politician Jean Allemane (1843-1935), were condemned to serve their sentence in the Fort Quélern, from April 1871 to March 1875.

[12][13] Even if it served as a prison, the Fort Quélern was above all intended to further strengthen the protection of the isthmus of the Roscanvel peninsula.