In 1622, several remonstrants, including the sons of Johan van Oldenbarnevelt, Reinier and Willem, conspired to assassinate Prince Maurice of Orange.
They were planning to hire a number of sailors to murder the prince during his trip from The Hague to Rijswijk to visit Margaretha van Mechelen.
Bontenbal was imprisoned in Rotterdam for eighteen weeks, but, despite being tortured, continued to deny that he was actively involved in the conspiracy.
On 3 July 1623, at around noon in Rotterdam, Bontenbal was led to the scaffold behind the council-hall, and was executed there at the age of 47 or 48 years old.
[1] Hugo de Groot was not aware of these developments in the Dutch republic because of his residence in Paris.