In 1271 he was again in Paris, lecturing to the students, managing the affairs of the church and consulted by the king, Louis VIII., his kinsman, on affairs of state.
He joined the rebellion of his kinsman Hugh, earl of Tyrone, but submitted in 1586.
Probably deprived of his office as chamberlainabout 1296 he may have shared the imprisonment of his kinsman, John de Baliol the king.
On his father's death in 85 or 86 he was placed under the guardianship of two fellowcountrymen, his kinsman Ulpius Trajanus (afterwards the emperor Trajan), and Caelius Attianus (afterwards prefect of the praetorian guard).
William's daughter, Wilhelmina, succeeded to the throne of Holland, but under the Salic law' the grand-duchy passed to his kinsman, Adolphus, duke of Nassau, who died in 1905, and was succeeded by his son William (b.