Courcy was constructed between 1658 & 1663 by Guillaume Le Berseur. However it was the significant renovation work by its third generation heir, Henri Auguste Hellouin, Marquis de Courcy, who rendered the current architectural design.
After the death of the marquis in 1791, followed by his only son in the Quiberon landings in 1795, Courcy was sold as a national property. There were several owners during the 19th century before the Gatellier family purchased the estate and remain owners to this day.
During the Second World War, Courcy was occupied by the Wertmartch then the SS. Unlike the neighboring castle of Fontenay-sur-Mer, Courcy was miraculously spared in battles and on D-day likely because :
- Courcy served as a rallying point for paratroopers
- Forces from both sides occupied Courcy between June 7 and 9th 1944, thus impossible to determine occupants at any one time.
- After the war , the greatest damage to the roof and east facade was from a direct hit from an American destroyer. The owner at that time, Professor Gatellier, succeeded in repairing the roof just before winter, thus avoiding fungus and rot. The shell head was salvaged from that hit and now serves as a counterweight in the rotisserie kitchen fireplace.