He tried for many years in Holland-Zeeland to enforce claims against the House of Wittelsbach but failed.
He led the traditional feuds of the House of Jülich and lost Kaiserswerth and Zülpich, among others.
He took part in the 1371 Battle of Baesweiler (in which Edward was mortally wounded) and captured Wenceslaus I, Duke of Luxembourg.
[2] His brother-in-law Reinald died later in 1371 and as neither Reinald nor Edward left heirs, another fight for the succession of Guelders arose between William and his wife Maria (sister to Reinald and Edward) and Maria's sister Mathilde, wife of John II, Count of Blois.
Among other territories, William acquired Monschau-Montjoie, Randerath and Linnich.