A 30 years war between the Catholics and the protestants that claimed about 8 million lives.

The Thirty Years’ War was a 17th-century religious conflict fought primarily in central Europe. It remains one of the longest and most brutal wars in human history, with more than 8 million casualties resulting from military battles as well as from the famine and disease caused by the conflict. The war lasted from 1618 to 1648, starting as a battle among the Catholic and Protestant states that formed the Holy Roman Empire. However, as the Thirty Years’ War evolved, it became less about religion and more about which group would ultimately govern Europe. In the end, the conflict changed the geopolitical face of Europe and the role of religion and nation-states in society.

Causes of the Thirty Years’ War.

With Emperor Ferdinand II’s ascension to head of state of the Holy Roman Empire in 1619, religious conflict began to foment.

One of Ferdinand II’s first actions was to force citizens of the empire to adhere to Roman Catholicism, even though religious freedom had been granted as part of the Peace of Augsburg.

Signed in 1555 as a keystone of the Reformation, the Peace of Augsburg’s key tenet was “whose realm, his religion,” which allowed the princes of states within the realm to adopt either Lutheranism/Calvinism or Catholicism within their respective domains.

This effectively calmed simmering tensions between peoples of the two faiths within the Holy Roman Empire for more than 60 years, although there were flare ups, including the Cologne War (1583-1588) and the War of the Julich Succession (1609).

Still, the Holy Roman Empire may have controlled much of Europe at the time, though it was essentially a collection of semi-autonomous states or fiefdoms. The emperor, from the House of Habsburg, had limited authority over their governance.

Peace of Westphalia

Over the course of 1648, the various parties in the conflict signed a series of treaties called the Peace of Westphalia, effectively ending the Thirty Years’ War – although not without significant geopolitical effects for Europe.

Weakened by the fighting, for example, Spain lost its grip over Portugal and the Dutch republic. The peace accords also granted increased autonomy to the former Holy Roman Empire states in German-speaking central Europe.

Legacy of the Thirty Years’ War

Ultimately, though, historians believe the Peace of Westphalia laid the groundwork for the formation of the modern nation-state, establishing fixed boundaries for the countries involved in the fighting and effectively decreeing that residents of a state were subject to the laws of that state and not to those of any other institution, secular or religious.

This radically altered the balance of power in Europe and resulted in reduced influence over political affairs for the Catholic Church, as well as other religious groups.

As brutal as the fighting was in the Thirty Years’ War, hundreds of thousands died as a result of famine caused by the conflict as well as an epidemic of typhus, a disease that spread rapidly in areas particularly torn apart by the violence. Historians also believe the first European witch hunts began during the war, as a suspicious populace attributed the suffering throughout Europe at the time to “spiritual” causes.

The war also fostered a fear of the “other” in communities across the European continent, and caused an increased distrust among those of different ethnicities and religious faiths – sentiments that persist to some degree to this day.

Read the full article here: www.history.com/.amp/topics/reformation/thirty-years-war