In 1618 two Catholic imperial councillors were thrown out of a window of Prague Castle (one of the so-called Defenestrations of Prague), signaling an open revolt by the Bohemian estates against the Habsburgs and started the Thirty Years' War. The Bohemian estates decided to levy an army, decreed the expulsion of the Jesuits, and proclaimed the Bohemian throne to be elective. They elected a Calvinist, Frederick of the Palatinate, to the Bohemian throne. Frederick then tried to muster further support for the Bohemian cause, even attempting to convince the Ottoman Empire to provide military support in exchange for tribute. On November 8, 1620, the Czech estates confronted the imperial forces in the Battle of White Mountain near Prague and were decisively defeated.