The couple married in Dordrecht in South Holland on 8 August 1617.
[1] In 1616, his main work, Oorsprong en voortgang der Nederlandtscher beroerten (Origin and progress of the disturbances in the Netherlands) about the Dutch Revolt, was published anonymously.
[2] It describes the crimes committed by the Spanish rulers under Philip II against the Dutch population.
The book is illustrated with depictions of atrocities that leave little to the imagination.
The reason Gijsius initially had the work published anonymously is because the book was published during the period of the Twelve Years' Truce with the Spaniards, and he did not wish to antagonise the proponents of that peace.