Mont-Saint-Michel rises from a tidal landscape on the coast of Normandy. Religious foundations and successive construction campaigns turned the island into an abbey and fortified settlement. Its isolation, changing access, and medieval defenses shaped a history in which pilgrimage, architecture, and warfare were closely connected.

Tidal island

The connection between Mont-Saint-Michel and the mainland has changed over the centuries. Previously connected by tidal causeway uncovered only at low tide, this was converted into a raised causeway in 1879, preventing the tide from scouring the silt around the mount. The coastal flats have been polderised to create pastureland, decreasing the distance between the shore and the island, and the Couesnon river has been canalised, reducing the dispersion of the flow of water. These factors have all encouraged silting-up of the bay.

In June 2006, French prime minister Dominique de Villepin and regional authorities announced a €200 million project (Projet Mont-Saint-Michel) to build a hydraulic dam using the waters of the Couesnon and the tides to help remove the accumulated silt, and to make Mont-Saint-Michel an island again. The construction of the dam began in 2009. The project included the removal of the causeway and its visitor car park. Since April 2012, the new car park on the mainland has been located 2.5 kilometres (1+1⁄2 mi) from the island. Visitors can walk or use shuttles to cross the bridge.

8th century onward

Before the construction of the first monastic establishment in the 8th century, the island was called Mont Tombe (tumba). According to a legend, the archangel Michael appeared in 708 to Aubert of Avranches, the bishop of Avranches, and instructed him to build a church on the rocky islet. Unable to defend his kingdom against the assaults of the Vikings, the king of the Franks agreed to grant the Cotentin Peninsula and the Avranchin, including Mont-Saint-Michel traditionally linked to the city of Avranches, to the Bretons in the Treaty of Compiègne. This marked the beginning of a brief period of Breton possession of the Mont. In fact, these lands and Mont-Saint-Michel were never really included in the duchy of Brittany. Around 989–990 these traditional bishoprics, dependent of the archbishopric of Rouen and that had been left vacant during the time of the Viking raids, regained their bishops.

14th century

Under the rule of the 29th abbot, Pierre le Roy, from 1386 to 1410, new fortifications were built: at the northeast corner of the Merveille, an octagonal crowning element was added to the Corbins tower; at its base, a long curtain wall-terrace overlooking the woods. In 1393, two turrets were added to flank the 1257 gate. Large steps were built in front of the barbican, and the abbot had a fortified residence built, as well as the square-based Pénine tower, designed to guard the Grand Degré.

When Louis XI of France founded the Order of Saint Michael in 1469, he intended that the abbey church of Mont-Saint-Michel become the chapel for the order, but because of its great distance from Paris, his intention could never be realized.

Abbey design

Robert de Thorigny, a great supporter of Henry II of England, who was also Duke of Normandy, reinforced the structure of the buildings and built the main façade of the church in the 12th century. In 1204, Guy of Thouars, regent for the Duchess of Brittany, as vassal of the King of France, undertook a siege of the Mount. After setting fire to the village and massacring the population, he beat a retreat under the powerful walls of the abbey. The fire which he lit extended to the buildings, and the roofs fell prey to the flames. Horrified by the cruelty of his Breton ally, Philip Augustus offered Abbot Jordan a grant for the reconstruction of the abbey in the new Gothic architectural style.