How did the Thirty years war begin

The Thirty Years' War was a war fought primarily in Central Europe between 1618 and 1648. One of the most destructive conflicts in human history, it resulted in eight million fatalities not only from military involvements but also from violence, famine, and plague.

Explanation:

It was fought in the central European territory of the holy roman empire. Although it was a religious conflict between the protestants and Catholics, the self-preservation of the Habsburg dynasty was also a central motive

The immediate cause which led to the Thirty Year's War was the revolt of the Protestants of Bohemians who were quite unhappy with Ferdinand II on account of his anti-Protestant policy. The trouble started when Ferdinand II ordered destruction of Protestant Church at Prague. The war soon developed into a devastating struggle for the balance of power in Europe.