The Protestant Reformation began on October 31, 1517 when Martin Luther (often called the father of Protestantism), a German theologian and religious reformer, published his "95 Theses" criticizing the Catholic Church. It led to the creation of new Christian groups like Lutheranism and Calvinism. The movement's influence persisted through the 16th and 17th centuries, with the Thirty Years' War (1618-1648) marking a significant turning point that paved the fragmentation of Western Christianity. The Peace of Westphalia, signed on 24 October 1648, is the most commonly mentioned terminuses of the Protestant Reformation era in Europe.