Thirty Years' War

An international conflict taking place in northern Europe from 1618 to 1648. The war was fought between Catholics and Protestants and also drew in the national armies of France, Sweden, Spain, Denmark, and the Habsburg dynasty that ruled the Holy Roman Empire. The roots of the conflict lay in the Protestant Reformation of the sixteenth century. The Reformation, strongly opposed by the Catholic Habsburgs, brought religious persecution and civil war to Germany. By the Peace of Augsburg, concluded in 1555, each German prince was free to choose the religious faith—either Lutheranism or Catholicism—to be followed in his own realm.

Religious conflict continued despite the Peace of Augsburg, complicated by the territorial ambitions of the nations surrounding Germany, then a patchwork of small and autonomous duchies, kingdoms, counties, margravates, and city-states. Sweden and Denmark, kingdoms to the north, were seeking new territory in northern Germany, while France was opposing Habsburg power in Germany and the Low Countries. Open warfare between Catholics and Protestants broke out in Swabia, a region of southwestern Germany, in the early 1600s. Protestant Calvinists formed the League of Evangelical Union, while Catholics gathered their forces into the Catholic League.

In 1619, Ferdinand of Styria became Ferdinand II, Holy Roman Emperor. His dedication to Catholicism and determination to stamp out Protestantism prompted a revolt in Prague, the capital of Bohemia. Two of the emperor's representatives were attacked and thrown out of a window after a trial, an act that sparked a general revolt against Ferdinand's authority in Bohemia and Hungary. To quell the rebellion, Ferdinand asked for help from his nephew, King Philip IV of Spain. Although Vienna, the Habsburg capital, came under siege by a Protestant army, Ferdinand won a victory against the Protestant Union at the Battle of Sablat in 1619. The Protestants of Bohemia responded by declaring Ferdinand deposed as their king and replacing him with Elector Frederick V of the Palatinate.

Spain then sent armies from Flanders to come to the emperor's assistance. Spanish armies marauded through the Protestant cities of western Germany, then joined up with the emperor to put down the rebellion in Austria. At the Battle of White Mountain on November 8, 1620, Ferdinand defeated the Protestant armies under Frederick V, a victory that permanently returned Bohemia to Habsburg control. Spanish armies then captured Mannheim, Heidelberg, and many other cities, executing or driving out their Protestant leaders.

The king of Denmark then came to the rescue of the Protestants by gathering a mercenary army, allying himself with England and France, and invading Germany. The Danes suffered two defeats at the Battle of Dessau Bridge in April 1626 and the Battle of Lutter in August 1626. By the Treaty of Lubeck in 1629, the Danes gave up their alliance with the Protestants and the Danish king was allowed to keep his throne. The Swedish king Gustavus Adolphus then intervened, fearing the growing Habsburg power in northern Germany. A brilliant military tactician, this king won several important battles, including the Battle of Breitenfeld in 1631. The Swedes won again at the Battle of Lutzen, but Gustavus Adolphus was killed in the battle.

The Peace of Prague of 1635 temporarily ended the fighting and granted a truce to the Protestant opponents of the emperor. After this, France entered the war on the Protestant side against the Habsburgs. Catholic Spain invaded France in retaliation. The war caused massive damage and heavy casualties on both sides, and after more battles in Bohemia and southern Germany the Truce of Ulm was signed in 1647. The Peace of Westphalia followed in the next year. Over the three decades of war, Germany was ravaged by fighting, pillaging, and widespread disease and famine. The nation would remain fragmented and weak for more than two centuries. Spain began a long decline that left it one of the weakest nations in Europe, and the republics of the Low Countries permanently broke away from Spanish control. Habsburg authority was also weakened in central Europe, while France, which saw little fighting, emerged as Europe's dominant power.

See Also: Habsburg dynasty; Reformation, Protestant