Guildo Castle, situated on a rocky outcrop overlooking the estuary of the Arguenon river, dates back to the early 13th century. It was preceded by a 12th century building, probably a manor. In the mid-14th century the castle was destroyed, probably during the War of the Breton Succession. It was rebuilt later that century. During the 15th century the castle was enlarged and embellished, probably because the Lady of Guildo; Françoise de Dinan, rose in status as she married Gilles de Bretagne; brother of the Dukes of Brittany Francis I and Peter II . . . In the following French Breton War Guildo Castle was destroyed, probably during the campaign of Louis I de la Trémoille on the northern coast of Brittany in 1489. After that the castle was only partially rebuilt. During the 16th century Guildo Castle was strengthened again and it was adapted to the use of artillery. Between 1590 and 1598, during the French Wars of Religion, the castle was besieged several times. After these sieges the castle was damaged so much that it was gradually abandoned and left to fall to ruin. During the 18th century the ruins were used for agricultural purposes. In 1794 it was sold and during the 19th century it served as a stone quarry.
Castles.nl (lots of photos)
Google Translate’s rendition:
The next phase sees the installation of the first stone castle, of which the remains of a dwelling leaning against the north curtain partially remain. Three stages of development can be distinguished, all prior to the last third of the 13th century . . . The third phase follows the destruction of the castle around the middle of the 14th century, probably during the War of the British Succession ( 1341-1364). After a phase of abandonment, the castle was rebuilt in the last quarter of the 14th century probably. The northern front sees the construction of a new dwelling, partially reusing the remains of previous constructions. This dwelling consists of a large lower room, and a set of apartments on three levels located to the east.
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[Evidence makes it possible] to situate the capture of the castle during the campaign of Louis I of La Trémoille on the north coast of Brittany in 1489. The chatelet is razed to ground level of the courtyard, resulting in the destruction of the forge. The polygonal tower is set on fire, as is the dwelling. The outbuildings, already partly destroyed for the defense are ruined, as well as the stable. Neither the outbuildings nor the north wing of the north house will be rebuilt. The new residence then concentrates on the eastern wing. A re-defence of the castle during the 16th century brought only minor modifications to it (installation of ramparts in the lower rooms. . . . Besieged several times during the Wars of the League, the castle suffered extensive damage. It is gradually being abandoned and slowly falling into disrepair. Its courtyard was leased and cultivated with corn from 1770. The discovery of a probable pigsty in the courtyard, although anecdotal, illustrates well the slow decline and the gradual abandonment of the site in the 17th and 18th centuries.