How did Johan van Oldenbarnevelt work with William the Silent during the Dutch revolt?

During the Dutch revolt, Johan van Oldenbarnevelt’s involvement in the movement for national liberation brought him into fairly close contact with William the Silent.1

As Oldenbarnevelt rose to prominence—serving as the pensionary of Rotterdam and participating in the negotiations for the Union of Utrecht—he became a key figure in the political coordination of the United Provinces. While he did not serve as William’s direct subordinate during the prince's lifetime, Oldenbarnevelt emerged as the primary trustee of William’s political legacy following the prince's assassination in 1584.12

After William's death, Oldenbarnevelt became the landsadvocaat (chief minister) of Holland, where he continued William’s work by integrating the new commonwealth of rebels and securing its international standing through alliances with France and England. In this capacity, he effectively acted as the union's foreign secretary, building upon the foundations laid by William to ensure the survival and independence of the Netherlands.23