The Fortifications of Saint-Quentin, or Feste Prinz Friedrich Karl form a fortification group in the Scy-Chazelles municipality located northwest of Metz on the Mont Saint-Quentin. Constituted by forts Diou and Girardin, the group is part of the first fortified belt of forts around Metz and had its baptism of fire in late 1944, when the Battle of Metz occurred.
The fortified group of forts known as Saint-Quentin belongs to the first fortified belt of Metz designed during Second French Empire by Napoléon III. The first fortified belt consists of Fort Saint-Privat (1870), Fort de Queuleu (1867), Fort des Bordes (1870), Fort de Saint-Julien (1867), Fort Gambetta, Déroulède, Fort Decaen, Fort de Plappeville (1867) and St. Quentin (1867), most of them unfinished or in skeletal form in 1870, when the Franco-Prussian War began. During the annexation, Metz oscillate between a German garrison of 15,000 and 20,000 men at the beginning of the period[1] and will exceed 25,000 men just before the First World War,[2] gradually becoming the premier stronghold of the German Reich.