extent of Protestantism occurred at some point between 1545 and 1620. In 1620, the Battle of White Mountain defeated Protestants in Bohemia (now the Czech Republic) who sought to have the 1609 Letter of Majesty upheld. . The Thirty Years' War began in 1618 and brought a drastic territorial and demographic decline when the House of Habsburg introduced counter-reformational measures throughout their vast possessions in Central Europe. Although the Thirty Years' War concluded with the Peace of Westphalia, the French Wars of the Counter-Reformation continued, as well as the expulsion of Protestants in Austria. According to a 2020 study in the American Sociological Review, the Reformation spread earliest to areas where Luther had pre-existing social relations, such as mail correspondents, and former students, as well as where he had visited. The study argues that these social ties contributed more to the Reformation's early breakthroughs than the printing press. Conclusion and legacy There is no universal agreement on the exact or approximate date the Reformation ended. Various interpretations emphasise different dates, entire periods, or argue that the Reformation never really ended. However, there are a few popular interpretations. Peace of Augsburg in 1555 officially ended the religious struggle between the two groups and made the legal division of Christianity permanent within the Holy Roman Empire, allowing rulers to choose either Lutheranism or Roman Catholicism as the official confession of their state. It could be considered to end with the enactment of the confessions of faith. Other suggested ending years relate to the Counter-Reformation or the 1648 Peace of Westphalia. From a Catholic perspective, the Second Vatican Council called for an end to the Counter-Reformation. In the history of theology or philosophy, the Reformation era ended with the Age of Orthodoxy. The Orthodox Period, also termed the Scholastic Period, succeeded the Reformation with the 1545–1563 Council of Trent, the 1562 Anglican Thirty-nine Articles, the 1580 Book of Concord, and other confessions of faith. The Orthodox Era ended with the development of both Pietism and the Enlightenment. The Peace of Westphalia might be considered to be the event that ended the Reformation. Some historians argue that the Reformation never ended as new churches have splintered from the Catholic Church (e.g., Old Catholics, Polish National Catholic Church, etc.), as well as all the various Protestant churches that exist today. No church splintering from the Catholic Church since the 17th century has done so on