[2] He fought in France as an ally of the English (he was the brother-in-law of King Edward III of England).

[3] In 1345, two months before he died, he besieged and took Utrecht [fr; nl], because the bishop, John van Arkel, was trying to regain the bishopric's historical independence from Holland.

William fought against the Saracens,[citation needed] and went on crusade with the Teutonic Order in Prussia.

[5] William was succeeded by his sister, Margaret of Hainaut, who was married to Louis IV, Holy Roman Emperor.

Hainaut, Holland and Zeeland became a part of the imperial crown domains.