The war began with the resistance and eventual revolt of Protestant nobles in Bohemia, which was under Hapsburg domination, against the Catholic King Ferdinand. It spread through Europe because of the constitutional frailty of the Holy Roman Empire, the inability of the German states to act in concert, and the ambitions of other European powers. The Catholic Princes were opposed to the Emperor. The Protestant rulers were divided among themselves between Lutheranism and Calvinism, and many of them were at odds for purely political reasons. …
