The Protestant Reformation Splits Europe

In 1517 Martin Luther, a German monk and professor, posted the Ninety-Five Theses, a list of objections to Catholic practices, especially the sale of indulgences, which were payments that supposedly reduced punishment for sin. He meant it as an academic challenge for a university debate, not a call to revolution. But the printing press changed the stakes entirely. Printers reproduced copies by the thousands, and within weeks Luther's arguments were circulating across German-speaking lands, read by ordinary people and local clergy who never set foot in his university. A local argument became a continent-wide movement almost overnight, because print let ideas travel faster than any single person could carry them.

The religious map of Europe kept shifting for over a century after 1517. Some rulers adopted Protestant teachings out of genuine conviction. But many saw a practical opportunity: break with Rome, and a king could confiscate monastery lands, stop sending tax revenue to the pope, and control religious appointments that once needed papal approval. That is why the Reformation cannot be explained as a theology dispute alone. It let monarchs convert spiritual independence into real wealth and power, which is exactly the problem rulers across the unit's gunpowder empires faced: how do you control belief across territory you cannot personally watch? Religious war followed, climaxing in the Thirty Years' War, and only ended with the Peace of Westphalia in 1648, which let each state's ruler set its religion.

This topic sits right after the gunpowder empires' territorial expansion because it shows the other half of imperial control: once land is seized, a ruler must also manage the loyalty and beliefs of the people living on it.