The Fortified Sector of Thionville (Secteur fortifié de Thionville) was the French military organisation that in 1940 controlled the section of the Maginot Line immediately to the north of Thionville. The sector describes an arc of about 25 kilometres (16 mi), about halfway between the French border with Luxembourg and Thionville. The Thionville sector was the strongest of the Maginot Line sectors. It was surrounded but not seriously attacked in 1940 by German forces in the Battle of France, whose main objective was the city of Metz. Despite the withdrawal of the mobile forces that supported the fixed fortifications, the sector successfully fended off German assaults before the Second Armistice at Compiègne. The majority of the positions and their garrisons finally surrendered on 27 June 1