William I of Guelders and Jülich

William
Duke of Guelders
Reign1377–1402
PredecessorReginald III
SuccessorReinald IV
Duke of Jülich
Reign1393–1402
PredecessorWilliam II
SuccessorReginald IV
Born5 March 1364
Died16 February 1402(1402-02-16) (aged 37)
Arnhem, The Netherlands
SpouseKatherine of Bavaria
HouseHouse of Jülich
FatherWilliam II, Duke of Jülich
MotherMaria of Guelders

William (5 March 1364 16 February 1402, Arnhem) was Duke of Guelders, as William I, from 1377 and Duke of Jülich, as William III, from 1393. William was known for his military activities, participating in the Prussian crusade five times and battling with neighbors in France and Brabant throughout his rule. His allies included Holy Roman Emperors, Charles IV and Wenceslaus, Richard II of England, and Conrad Zöllner von Rothenstein, the Grand Master of the Teutonic Knights. During his reign the duchies of Guelders and Jülich were temporarily unified.