In 1350, with encouragement from his mother, Edward began a devastating civil war against his brother Reginald III for control of the Duchy of Guelders.
Upon Edward's death, his brother Reginald III regained the Duchy of Guelders but died shortly afterwards, on 4 December 1371.
As neither Edward nor Reginald had children, another war of succession for Guelders began, with the Bronkhorster faction supporting Edward and Reginald's half-sister Maria, wife of William II of Jülich, and the Heerkeren faction supporting their half-sister Mathilde, wife of Count John II of Blois.
In 1377, Emperor Charles IV awarded the Duchy of Guelders and the County of Zutphen to Maria's son William of Jülich.
After her total defeat in the Battle of Hönnepel on 24 March 1379, Mathilde renounced her claim to Guelders and Zutphen.