William was born in 1307, the son of William I of Hainaut and Joan of Valois. In 1334, he married
Joanna, Duchess of Brabant, the daughter and heiress of
John III, Duke of Brabant, but had no issue. He fought in
France as an ally of the
English (he was the brother-in-law of King
Edward III of England). In 1339, William participated in the
Siege of Cambrai (1339). In 1345, two months before he died, he , because the
bishop,
John van Arkel, was trying to regain the
bishopric's historical independence from Holland. William fought against the
Saracens, and went on crusade with the
Teutonic Order in Prussia. He was killed near
Stavoren, during one of the battles of
Warns against the
Frisians in 1345. 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. ==References==