On the Laws of War and Peace.
Along with his patron Barneveldt, he was arrested in 1618 for supporting the Remonstrants, but escaped prison with the help of his wife and fled to France, where Louis XIII gave him a pension. An author of histories, religious works, and verse, his  tragedy Adam's Exile was much admired by Milton, though he is best known today for a legal work. FTP, name this Dutch writer, who appealed to natural law and the social contract in his 1625 masterpiece, On the Laws of War and Peace.
Along with his patron Barneveldt, he was arrested in 1618 for supporting the Remonstrants, but escaped prison with the help of his wife and fled to France, where Louis XIII gave him a pension.
Hugo Grotius (accept Huig de Groot)