Thirty Years' War (1618–1648): Europe's Most Destructive War

The Thirty Years’ War was a series of conflicts fought mainly in the Holy Roman Empire between 1618 and 1648, beginning as a Protestant revolt in Bohemia and widening into a struggle that drew in Denmark, Sweden, France, Spain and many German states. It was one of the most destructive wars in European history: millions died, largely from famine and disease, and parts of Germany lost half their population. The war ended with the Peace of Westphalia, which reshaped the political map of Central Europe.

Background: a divided Empire

The Holy Roman Empire was a patchwork of hundreds of territories under an elected emperor, by this time always a member of the Austrian Habsburg family. The Peace of Augsburg of 1555 had allowed each Lutheran or Catholic prince to choose the religion of his lands, but it ignored Calvinism and left disputes over church property unresolved.

By the early seventeenth century these tensions had hardened into rival alliances. Calvinist and Lutheran princes formed the Protestant Union in 1608, led by the Elector Palatine; Catholic states answered with the Catholic League in 1609, led by Duke Maximilian of Bavaria. Imperial institutions were increasingly paralysed.

In Bohemia, a Habsburg kingdom with a strong Protestant nobility, Emperor Rudolf II had granted religious freedom in the Letter of Majesty of 1609. When the devoutly Catholic Archduke Ferdinand of Styria was accepted as king-designate in 1617, Protestant nobles feared these rights would be taken away.

The Bohemian revolt (1618–1623)

On 23 May 1618 Protestant nobles threw two royal governors and a secretary from a window of Prague Castle, the Defenestration of Prague. They set up their own government and raised an army. In August 1619 the Bohemian estates deposed Ferdinand and elected the Calvinist Frederick V, Elector Palatine, as their king; days later Ferdinand was elected Holy Roman Emperor as Ferdinand II.

Ferdinand secured help from Maximilian of Bavaria, Spain and the Lutheran Elector of Saxony. On 8 November 1620 the Catholic League’s army under the Count of Tilly crushed the Bohemian forces at the Battle of White Mountain outside Prague. Frederick fled, mocked as the “Winter King”, and Spanish and Bavarian troops occupied his Rhineland lands. In 1623 his electoral title was transferred to Maximilian.

In Bohemia the victory was followed by executions of rebel leaders, confiscation of noble estates and forced re-Catholicisation. Thousands of Protestants went into exile.

The Danish phase (1625–1629)

In 1625 King Christian IV of Denmark, who was also Duke of Holstein in the Empire, entered the war to defend the Protestant cause and his own interests in northern Germany. Ferdinand now had a second army raised by the Bohemian nobleman Albrecht von Wallenstein, who financed his huge force by levying contributions from the territories it occupied.

Wallenstein defeated the Protestant commander Ernst von Mansfeld at Dessau Bridge in April 1626, and Tilly beat Christian IV at Lutter in August 1626. Imperial troops overran much of northern Germany and Jutland. Denmark made peace at Lübeck in 1629.

At the height of his power, Ferdinand issued the Edict of Restitution in March 1629, ordering the return of church lands secularised since 1552. The edict alarmed even Lutheran princes who had supported the emperor and helped prolong the war.

The Swedish phase (1630–1635)

In 1630 King Gustavus Adolphus of Sweden landed in Pomerania with a well-trained army. He wanted to protect Swedish interests on the Baltic and support German Protestants, and from 1631 he received subsidies from Catholic France under Cardinal Richelieu.

In May 1631 Tilly’s army stormed and sacked the Protestant city of Magdeburg, where most of the population, perhaps 20,000 people, died in the assault and fire. Shocked Protestant princes, including Saxony, joined Sweden. In September 1631 Gustavus routed Tilly at Breitenfeld near Leipzig, then swept into southern Germany. Tilly was mortally wounded in 1632.

Ferdinand recalled Wallenstein, whom he had dismissed in 1630. At Lützen on 16 November 1632 the Swedes won the field, but Gustavus Adolphus was killed. The Swedish chancellor Axel Oxenstierna kept the war going. Wallenstein, suspected of secret negotiations, was murdered by his own officers at Eger (Cheb) in February 1634 with the emperor’s approval.

In September 1634 an imperial and Spanish army destroyed the main Swedish force at Nördlingen. Most German Protestant states, led by Saxony, then made peace with the emperor in the Peace of Prague of 1635.

The French and Swedish phase (1635–1648)

The Peace of Prague might have ended the war in Germany, but France would not accept a Habsburg victory. In 1635 France declared war on Spain and began fighting directly in Germany alongside Sweden. The war became chiefly a contest between the French Bourbons and the Spanish and Austrian Habsburgs, fought on German soil.

Armies marched back and forth for years, living off a ruined countryside. Swedish forces under commanders such as Johan Banér and Lennart Torstensson won major victories, including Second Breitenfeld in 1642 and Jankau in 1645, while the French defeated Spain at Rocroi in 1643. Spain, meanwhile, faced revolts in Catalonia and Portugal from 1640.

Peace talks opened in the Westphalian cities of Münster and Osnabrück in the mid-1640s, but fighting continued alongside them. The last action of the war in the Empire was a Swedish siege of Prague in 1648, where the conflict had begun.

The Peace of Westphalia

The Peace of Westphalia, signed on 24 October 1648, ended the war in the Empire. It extended the Augsburg settlement to Calvinists, fixed 1624 as the “normal year” for deciding church property and religious rights, and confirmed the princes’ right to make alliances so long as these were not directed against the emperor.

The negotiations were a huge diplomatic undertaking. More than a hundred delegations attended, representing the emperor, the European crowns and many German princes and cities, with France and the Catholic powers negotiating mainly at Münster and Sweden and the Protestants at Osnabrück. The papal representative objected to the religious terms, but his protests were ignored.

Sweden received western Pomerania and other territories on the Baltic and North Sea coasts, and France gained rights in Alsace and confirmation of the bishoprics of Metz, Toul and Verdun. The independence of the Dutch Republic and the Swiss Confederation was recognised. The separate war between France and Spain went on until the Peace of the Pyrenees in 1659.

Warfare and its human cost

The war was fought largely by mercenary armies recruited by military entrepreneurs, who raised regiments on credit and expected to be repaid by the rulers who employed them. Wallenstein perfected a system of “contributions”, forcing occupied towns and districts to pay, feed and house the troops, which allowed armies to grow far beyond what rulers could afford from taxes.

Armies of tens of thousands of soldiers were followed by baggage trains of wives, children, servants and traders that could be as large as the armies themselves. Gustavus Adolphus introduced lighter field guns, smaller and more flexible infantry units and closer cooperation between musketeers, pikemen and cavalry, ideas soon copied by others. Sieges, raids and foraging were far more common than set-piece battles.

Battles were only a small part of the suffering. Unpaid armies lived by plunder, and soldiers spread typhus, plague and dysentery. Peasants fled their villages, harvests were lost and towns were sacked or burned.

Modern estimates of total deaths range from about 4.5 to 8 million. Historians such as Peter Wilson suggest the Empire’s population fell by around 20 per cent, from roughly 20 million, while older estimates proposed losses of a third or more. Regions on the main campaign routes, such as Pomerania, Mecklenburg and Württemberg, lost half or more of their inhabitants. Recovery took decades.

Myths and facts

Myth: It was a purely religious war. Religion mattered greatly, but Catholic France allied with Protestant Sweden, and Lutheran Saxony fought for the Catholic emperor at the start.

Myth: Westphalia created the modern system of sovereign states. Political scientists long described a “Westphalian system”, but historians point out that the treaties preserved the Empire and its courts rather than abolishing them.

Myth: Germany lost two-thirds of its people. Such figures, common in the nineteenth century, are now thought too high, though some districts did suffer losses on that scale.

Timeline

• 1618, 23 May: The Defenestration of Prague begins the Bohemian revolt.
• 1619, August: Frederick V is elected king of Bohemia; Ferdinand II becomes emperor.
• 1620, 8 November: The Catholic League wins the Battle of White Mountain.
• 1626, August: Tilly defeats Christian IV of Denmark at Lutter.
• 1629, March: Ferdinand II issues the Edict of Restitution.
• 1630, July: Gustavus Adolphus lands in Pomerania.
• 1631, 17 September: Swedish and Saxon victory at Breitenfeld.
• 1632, 16 November: Gustavus Adolphus is killed at Lützen.
• 1635: The Peace of Prague; France declares war on Spain.
• 1648, 24 October: The Peace of Westphalia is signed.

Why it matters

The Thirty Years’ War devastated Central Europe and left a lasting memory of catastrophe in German culture. Its settlement weakened the emperor, confirmed religious coexistence within the Empire, raised Sweden and France to the first rank of powers and marked the beginning of the end of Spanish dominance in Europe.