European wars of religion

For roughly two centuries, starting in the 1500s and stretching into the early 1700s, a series of conflicts known as the European wars of religion tore through the continent. These wars erupted after Martin Luther’s Protestant Reformation kicked off in 1517, shaking up the religious and political structures of Europe’s Catholic nations.

While faith was a key factor, other motivations—like rebellion, land grabs, and rivalries between major powers—also fueled the fighting. A notable twist came near the end of the Thirty Years’ War (1618–1648), when Catholic France sided with Protestant forces against the Catholic Habsburgs. The Peace of Westphalia, signed in 1648, largely put a stop to the main conflicts and introduced a new political framework now called Westphalian sovereignty.

The violence began with smaller clashes: the Knights’ War (1522–1523) and the larger German Peasants’ War (1524–1525) in the Holy Roman Empire. Things escalated after 1545, when the Catholic Church launched the Counter-Reformation to push back against Protestant growth.

Thirty Years' War

The fighting peaked with the Thirty Years’ War, which ravaged Germany and wiped out a third of its people. The Peace of Westphalia helped calm things by officially recognizing three Christian traditions within the Holy Roman Empire: Roman Catholicism, Lutheranism, and Calvinism. Even so, smaller religious wars dragged on in Western Europe into the 1710s, including the Wars of the Three Kingdoms (1639–1651) in the British Isles, the Savoyard–Waldensian wars (1655–1690), and the Toggenburg War (1712) in the Western Alps.

Definitions and discussions

These wars are sometimes called the Wars of the Reformation. In 1517, Martin Luther’s Ninety-five Theses spread across Europe in just two months, thanks to the printing press, outpacing the ability of Holy Roman Emperor Charles V and the papacy to stop them. Luther was excommunicated in 1521, which cemented the split in Western Christendom between the Roman Catholic Church and the Lutherans, and opened the door for other Protestant groups to defy papal authority.

Even after the Peace of Westphalia, religious conflicts continued into the 1700s, like the Savoyard–Waldensian wars (1655–1690), the Nine Years’ War (1688–1697)—which included the Glorious Revolution and the Williamite War in Ireland—and the War of the Spanish Succession (1701–1714). Whether these count as part of the European wars of religion depends on how you define a “war of religion” and whether you see them as European (international) rather than domestic affairs.

Scholars have debated how religious these wars really were, pointing to other factors like national identity, dynastic ambitions (many were also wars of succession), and financial interests. Some conflicts from the same period weren’t sparked by Reformation disputes at all—for example, the Italian Wars (1494–1559) involved only Catholics, and the Northern Seven Years’ War (1563–1570) involved only Lutherans. Others note that alliances often crossed religious lines: Lutheran duke Maurice of Saxony helped Catholic emperor Charles V in the first Schmalkaldic War in 1547 to become Saxon elector instead of his Lutheran cousin John Frederick, while Catholic king Henry II of France backed the Lutherans in the second Schmalkaldic War in 1552 to secure French bases in Lorraine. The Encyclopædia Britannica sums it up by saying these wars were “fought mainly for confessional security and political gain.”

In the late 1900s, revisionist historians like William M. Lamont argued that religion was the main driver behind the Wars of the Three Kingdoms (1639–1653), while John Morrill (1993) called them “the last of the Wars of Religion” rather than Europe’s first revolution. This view faced criticism from historians like Glen Burgess, who studied Parliamentarian political propaganda. He found that while many Puritans took up arms against the religious reforms of Charles I, they often framed their rebellion as a response to a king who broke key constitutional rules and had to be removed.

They even warned fellow Parliamentarians not to lean too heavily on religious arguments when justifying war against the monarch. It’s possible that religious motives were hidden behind legal language, like defending the Church of England as the national church. Seen that way, the Parliamentarians’ legal-constitutional arguments weren’t a denial that the struggle was religious—they were actually a way of saying it was.