How the Reformation Spread

Earlier reformers, like Jan Hus a century before, got crushed in one valley. Luther did not, mainly because of the printing press. His 1517 objection to indulgences, the Ninety-Five Theses, was copied, translated, and distributed across German-speaking lands within weeks. Through the 1520s, Luther's pamphlets were written in plain German, cheap to print, and read aloud to the illiterate, so his ideas crossed village lines before any bishop could respond. Territory followed text: year by year, princes across the Holy Roman Empire declared their lands Lutheran, and by the 1530s a patchwork of Lutheran states ran through Saxony, Hesse, and much of the north.

Princes converted for reasons beyond conscience. Declaring Lutheranism let a prince seize local Catholic Church property, stop sending revenue to Rome, and control religious life inside his own territory instead of answering to a pope. The Peace of Augsburg, signed in 1555, legalized this arrangement. It let each prince choose Catholicism or Lutheranism for his own territory, a principle later shorthanded as cuius regio, eius religio: whose realm, his religion. Subjects who disagreed could emigrate, but they could not simply practice differently where they lived.

That settlement only covered princes and Lutherans, leaving Calvinists and the deeper tensions unaddressed, which is why religious war returns within a lifetime. It also exposed a gap inside Luther's own movement: his freedom was theological, a conscience answerable to God alone, not a license to upend the social order, as the Peasants' Revolt of 1525 proved when he turned against the very people using his words.