 The Thirty Years War began in 1618 when the Protestant-dominated Bohemian Estates offered the Crown of Bohemia to Frederick of the Palatinate, rather than the conservative Catholic, Emperor Ferdinand II.Most of the Holy Roman Empire remained neutral, viewing it as an inheritance dispute, and the revolt was quickly suppressed.However, when Frederick refused to admit defeat, Imperial forces invaded the Palatinate and forced him into exile; removal of a hereditary prince changed the nature and extent of the war.