Wilhelm was a member of a minor comital family from the region of the Meuse (Maas) valley.
[1] He was active in Cologne as the elector-archbishop's secretary under his predecessor Walram von Jülich and was one of his most important advisers.
The King and Emperor Charles IV was opposed to his nomination, but Wilhelm had the support and protection of Brabant and France, and was duly appointed by Pope Clement VI.
Wilhelm was an unusually efficient ruler, and soon managed to stabilise the archbishopric's financial position, which was the prerequisite for the effective exercise of its territorial powers.
He not only established political relations with France, England and north-west Europe, but was apparently involved in the formulation of the Golden Bull of Charles IV in 1356.