When the treaty resulted in Protestantism gaining ground, notably in Brussels, Ghent and Bruges, he abandoned the cause of the rebels for the king on 3 March 1580, with the support of the city of Groningen, according to tradition convinced by his sister Cornelia van Lalaing.
Da traktaten resulterede i, at protestantismen vandt fremgang, især i Bruxelles, Gent og Brugge, forlod han oprørernes sag den 3. marts 1580 med støtte fra byen Groningen ifølge traditionen overbevist af sin søster Cornelia van Lalaing.