Richilde, Countess of Hainaut

Richilde, Countess of Mons and Hainaut (c. 1018 – 15 March 1086), was Countess consort and Regent of Flanders.

Richilde was either the daughter-in-law of Regnier V Count of Hainault. She was born c. 1018. She was married firstly to Herman of Mons who was Count of Hainault. (Count of Hainaut), c. 1040. After the death of Herman, Richilde married Baldwin, eldest son of Baldwin V of Flanders. Her husband Baldwin became count of Flanders (as Baldwin VI) in 1067, and ruled both Hainaut and Flanders until his death on 17 July 1070. Before his death, Baldwin VI left Flanders to their eldest son, Arnulf III, and Hainaut to their younger son, Baldwin II, with the provision that if either son preceded the other in death, he would inherit the other's county as well. Baldwin VI also obtained assurances from his brother Robert who gave his oath of homage and promised to protect his nephew. After Baldwin VI's death their son Arnulf III became Count of Flanders, but as he was a minor, Richilde served as Regent of Flanders.

Almost immediately Arnulf's uncle, Robert the Frisian, broke his oath to his brother Baldwin VI and disputed Arnulf's right to Flanders. Richilde asked for help from William Fitzosbern of Normandy who married her. Despite help from King Philip I of France, her forces were defeated at the Battle of Cassel and William Fitzosbern was killed along with her oldest son, Arnulf. Richilde herself was captured and released, King Philip later recognized Robert as Count of Flanders.

Richilde and her younger son, Baldwin II, retained Hainaut, but made subsequent unsuccessful attempts to recover Flanders. Richilde built the castle at Beaumont along with a chapel there dedicated to St. Venantius. She, along with her son Baldwin, founded the monastery of Saint-Denis-en-Broqueroie. At the end of her regency she retired to the Abbey of Messines. Richilde died on 15 March 1086.