John William of Cleves Johann Wilhelm Wilhelm - Johann Wilhelm of Cleves

From the book Anna, Duchess of Cleves: The King's Beloved Sister written by Heather R. Darsie who is an historian specializing in Early Modern history of Germany and England. "On 14 September 1584, Johann Wilhelm was engaged to Jakobe von Baden. They wed on 16 June 1585 in the chapel of the rebuilt Dusseldorf castle. Their marriage was an utter disaster. At some point before the marriage, Johann Wilhelm began a long-term affair with a woman of low social rank named Anna op den Graeff. The relationship was known to have produced one illegitimate son, Herman op den Graeff, born in 1585"