The Thirty Years' War was one of the most horrific conflicts in history, and though it is widely viewed as a religious struggle, that was only part of the complicated war. Calvinists and Lutherans did not get along, and both persecuted some of the more radical Anabaptist sects. At the same time, one major motivation behind the war was Holy Roman Emperor Ferdinand II’s determination to rule all of the empire and not be just a figurehead. There were struggles between rulers and their estates over power, and Catholic France later entered the war on the side of the Protestants in order to counter the Habsburgs’ power.
The Battle of Breitenfeld, fought in September 1631, was the first major Protestant victory and widely considered the crowning achievement of Swedish King Gustavus Adolphus’ military career. Through his establishment of communication and supply lines at strategic points across the Baltic Sea, the securing of Protestant alliances, and his use of combined arms, amongst his other trademark techniques, the Swedish forces, against all odds, defeated their rivals. Such was the devastation inflicted upon their opponents that the Count of Tilly, the chief commander of the Catholic League's armies, had no other choice but to retreat. 6,000 or so Catholic soldiers were captured, many of them later incorporated into the Protestant forces. Whatever remained of the survivors vanished into the dark of the night.
Gustavus’s triumph at Breitenfeld was a great victory that permanently affected the war, and for a time the Swedes were the most powerful military force in Central Europe, but Gustavus’s life ended slightly more than a year after the battle. On November 16, 1632, the king led a Protestant army of Swedes and German allies against Wallenstein’s army near Lützen in Saxony, and during a hard-fought Protestant victory that forced Wallenstein to retreat, Gustavus was killed while leading a cavalry charge.
