section_path: Spread
section_name: Spread
paragraph_text: Spread
  
  The Reformation spread throughout Europe beginning in 1517, reaching its peak between 1545 and 1620. The greatest geographical 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.