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 having set fire to the village and having massacred the population, he was obliged to beat a retreat under the powerful walls of the abbey. Unfortunately, the fire which he himself lit extended to the buildings, and the roofs fell prey to the flames. Horrified by the cruelty and the exactions of his Breton ally, Philip Augustus offered Abbot Jordan a grant for the reconstruction of the abbey in the new Gothic architectural style.