ใครแต่งงานกับRobert I, Count of Flanders?

Robert I (c. 1035 – 13 October 1093), known as Robert the Frisian, was count of Flanders from 1071 until his death in 1093. He was a son of Baldwin V, Count of Flanders, and the younger brother of Baldwin VI, Count of Flanders. He usurped the countship after defeating his nephew Arnulf III and his allies, which included King Philip I of France, Count Eustace of Boulogne and the counts of Saint-Pol and Ardres at the Battle of Cassel. He subsequently made peace with Philip, who became his stepson-in-law, but remained hostile to his sister Matilda and her husband William the Conqueror, who was king of England and duke of Normandy.

Gertrude of Saxony (c. 1030 – August 4, 1113), also known as Gertrude Billung, was a countess of Holland by marriage to Floris I, Count of Holland, and countess of Flanders by marriage to Robert I, Count of Flanders. She was regent of Holland in 1061-1067 during the minority of her son Dirk V, and regent of Flanders during the absence of her spouse in 1086–1093.