Defenestration of Prague, incident of Bohemian resistance to Habsburg authority that took place on May 23, 1618, preceding the beginning of the Thirty Years’ War. In 1617 Roman Catholic officials in Bohemia closed Protestant chapels that were being constructed by citizens of the towns of Broumov and Hrob, thus violating the guarantees of religious liberty laid down in the Letter of Majesty (Majestätsbrief) of Emperor Rudolf II (1609).
In response, the defensors, appointed under the Letter of Majesty to safeguard Protestant rights, called an assembly of Protestants at Prague, where the imperial regents, William Slavata and Jaroslav Martinic, were tried and found guilty of violating the Letter of Majesty and, with their secretary, Fabricius, were thrown from the windows of the council room of Hradčany (Prague Castle) on May 23, 1618. Although inflicting no serious injury on the victims, that act, known as the Defenestration of Prague, was a signal for the beginning of a Bohemian revolt against the Habsburg emperor Ferdinand II, which marked one of the opening phases of the Thirty Years’ War.