Defenestration of Prague, incident ofBohemian resistance to Habsburg authority that took place on May 23, 1618, preceding the beginning of theThirty Years’ War. In 1617 Roman Catholic officials inBohemia 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 theLetter of Majesty (Majestätsbrief) of EmperorRudolf II (1609).

In response, the defensors, appointed under the Letter of Majesty tosafeguard Protestant rights, called an assembly of Protestants atPrague, where the imperial regents,William Slavata andJaroslav 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 emperorFerdinand II, which marked one of the opening phases of the Thirty Years’ War.