The introduction of printing by the German inventor Johannes Gutenberg contributed to the formation of a new understanding of faith and reason. At this time, the German monk Martin Luther pushed for reforms within the Catholic Church. Luther's efforts culminated in the Protestant Reformation. The resulting religious schism was a leading cause of the Thirty Years' War, a conflict that tore apart the Holy Roman Empire and led to the death of millions of Germans. The terms of the Peace of Westphalia (1648) ending the war, included a major reduction in the central authority of the Holy Roman Emperor. Among the most powerful German states to emerge in the aftermath was Protestant Prussia, under the rule of the House of Hohenzollern.