 Suárez and Mariana formulated theories of resistance to unacceptable rulers, which Roman Catholic thinkers engaged in opposing Protestantism and Protestant rulers like James I (England) found attractive. In the heated atmosphere of the times, it is possible that these theories may have inspired the Catholic fanatics who assassinated Henry III (Valois), Henry IV (Bourbon), and William the Silent (Nassau). Similar theories were also developed by Protestant writers, including French Huguenots and Calvinists in the Low Countries.