Robert Curthose was the eldest son of William the Conqueror and Matilda of Flanders. Born around 1054, he became the Duke of Normandy in 1087 after his father's death. Robert was known for his adventurous spirit and military ambitions, often seeking to expand his territories. Despite his noble lineage, Robert struggled with leadership and faced challenges in maintaining control over Normandy. He participated in the First Crusade but returned to find his duchy in turmoil. Ultimately, he lost his title and lands to his younger brother, Henry I of England, and spent his later years in captivity.