Gisors is the key to Normandy according to Orderic Vital. In the 12th century it commanded a system of deep defences of a dozen castles distributed throughout the region from the Epte to the Andelle against the castles of Chaumont, Trie and Boury in the French Vexin district.
Gisors was the constant prey of conflicts between the French king and the duke of Normandy. In 1089, Robert Courtehose abandoned it to king Philippe I as the price for his alliance against William Rufus. Once again in the hands of the Duke of Normandy, the town and the Norman Vexin region were once again returned to the king of France between 1144 and 1151 by Geoffroi d'Anjou in homage for the duchy of Normandy. In 1160, Henri II Plantagenet took these prizes and retained them in the dowry of Marguerite de France, who married his son Henri the Younger. On the prince's death in 1183, Henri II refused to submit to the requisitions of Philippe Auguste who finally took the location in 1193.
The castle of Gisors was built by Robert de Bellême for William Rufus in 1096-1097. This is a polygonal stone tower raised on a motte closely guarded at its summit by a wall, the "curtain wall", an innovation subsequently adapted with all the neighbouring keeps. The defence was supplemented in the 1120s, under Henri I Beauclerc, by a low enclosure flanked by square towers. Henri II Plantagenet added two floors to the keep and reinforced the low enclosure in c. 1170-1180. Richard the Lion Heart, and then Philippe Auguste, completed the picture. Philippe Auguste in particular added a large cylindrical keep which dominates the outer wall near the entry to the bailey ('la Tour du Prisonnier' or Prisoner's tower). Other alterations were applied in the 14th, 15th and 16th centuries.
As a key fortification, the castle was also a royal residence as evidenced by the outbuildings and chapel dedicated by Henri II to saint Thomas Becket whose Romanesque chevet is built into the wall of the enclosure wall at the top of the motte.
- Beck, Bernard. - Châteaux forts de Normandie. - Rennes : Ed. Ouest-France, 1986
- Mesqui, Jean. "Gisors", Châteaux et fortifications en France. - Paris : Flammarion, 1997, p. 186-189
- “ Le château de Gisors ”, L’architecture normande au moyen âge, actes du colloque de Cerisy-la-Salle, septembre 1994. - Caen : Presses de l'Université. Condé-sur-Noireau : Ch. Corlet, 1997, pages 280-281
- Levé, Michel. -“ La frontière de l’Epte ”, Au temps des Plantagenêts, Connaissance de l’Eure, n° 89-90, 1993