Formulate an answer to this elaborate question: Johan van Banchem, was one of the leaders of the lynching of Johan de Witt and Cornelis de Witt on August 20, 1672, he was rewarded for this crime with an appointment as "baljuw" of The Hague by which office of steward, designated a medieval official and then a national leader, William III?
The answer to this question is:
Stadtholder