History and description

The first modern fortifications were erected at Ambleteuse in the 16th century, during the English occupation of Boulonnais (1540-1546). The port saw the creation of a pentagonal citadel including a barracks and partially surrounded by a fortified urban wall including two bastions and a sea wall, flanked by an artillery battery. Two dykes were constructed along the access channel to the port. The island contained within this port was surrounded by a non-fortified wall on three of its four sides. These constructions date back to 1544-1546.
In 1685, Vauban chose this site to build a coastal defensive battery, which was installed along the defensive sea wall, near to an area of reefs, and replaced the former English-installed battery. The standard battery: a low-lying semicircular artillery installation with cannon embrasures surmounted by a square tower at three levels. The final level served as an artillery platform. The tower housed the soldiers’ quarters and the magazines they needed (powder, supplies, etc.). A third artillery battery was added on one of the levels of the tower, in an arched annular emplacement. Two guardrooms and one first rampart flanked the tower. Work at the site was completed in 1690, during the war of the League of Augsbourg. A basin project, dated from the same year, did not come to fruition.
Once abandoned, the fort dubbed Mahon was put back into service by Napoléon I as part of the Boulogne camp, preparing for the landing in England in 1805. During the Second World War, the Germans built a concrete emplacement at the summit and included the tower in the Atlantic wall.

Current state

The fortifications and the English forts have been dismantled. Today, the bay of the port is filled in by the alluviums of Sprackle, the local river. All that is left is the tour Mahon, restored after 1945. Today, it houses a museum dedicated to the geographical exploration of the coast.


50° 48' 35.51" N, 1° 36' 26.442" E

coastal tower bolstered by a low-lying artillery installation
Sébastien le Prestre de Vauban
  • FAUCHERRE (N.), HANSCOTTE (F.), La route des fortifications de Vauban en Nord, Paris, 2003.
  • LE SALLE (G), « Ambleteuse, son port et son fort » in Les dessous de l’histoire boulonnaise, Boulogne-sur-Mer, juin 1983, p. 3-7.
  • Ouvrage collectif, Vauban et ses successeurs sur les côtes de la Manche, Paris, 2003.
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