Most modern histories of the Thirty Years' War portray it as an almost uniquely brutal conflict. Does it deserve this grim reputation?

The Thirty Years’ War claimed the lives of at least 5 million people – so, yes, its grim reputation is well deserved. In fact, the population of the Holy Roman Empire, the conflict’s main theatre, did not recover its prewar levels until around 60 years after the war ended. Through a combination of plague, famine and violence, the conflict brought misery to people living across vast swathes of central Europe.


The violence was, in many ways, a product of the large numbers of actors involved in the conflict. Beginning in 1618, the Thirty Years’ War was, at heart, a struggle for constitutional and religious power within the Holy Roman Empire – Europe’s largest and most populous state. It pitted the Austrian Habsburg family and their predominately Catholic supporters against a number of Protestant states in an increasingly bitter conflagration that would pull in foreign powers such as Denmark, Sweden and France.

There were any number of examples of atrocities perpetrated during the war but surely the most terrible was the sack of the Protestant city of Magdeburg (in modern north-east Germany) on 20 May 1631. The bloodshed was the culmination of a seven-week siege of the city by Catholic forces under a septuagenarian leader called Count Tilly. Tilly had repeatedly demanded Magdeburg’s surrender – and its people had repeatedly refused. When his soldiers finally breached the walls and infiltrated the city, their revenge was terrible. By the end of the day only 200 of the 1,900 buildings remained undamaged. Around four-fifths of the city’s 25,000 inhabitants were dead, many suffocated in their cellars as they hid from the shelling, fighting and plundering, but others cruelly murdered or dragged away by the victors.

More than any other event, the sack of Magdeburg has come to epitomise the Thirty Years’ War’s reputation as an orgy of uncontrolled violence.

What was the background to the conflict?

Unlike England, France or Spain, the Holy Roman Empire was governed as a ‘mixed monarchy’ in which the emperor shared power with around 60 princes, 140 counts and abbots, and 60 free cities.

The empire had long been dominated by the Habsburgs. Their hereditary principalities comprised a third of the empire, and the emperor had been chosen from their ranks since 1438. But during the 17th century, the Habsburgs were distracted by an internal family quarrel, as well as impending bankruptcy. This created a political vacuum, which was filled by the empire’s second most powerful family, the Wittelsbachs.

But there was another issue convulsing the empire – and that was the fall-out from the Reformation. Back in 1555, in the wake of this enormous rift in the established church, the empire’s power brokers had reached a peace treaty (the so-called Peace of Augsburg) in a bid to defuse growing tensions between Catholics and Protestants.

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One of the Peace of Augsburg’s principal diktats was that lands comprising a seventh of the empire’s territory should be reserved for Catholic rulers. By the early 17th century, many Protestants were claiming that this “ecclesiastical reservation” disadvantaged them politically, and frustrated their efforts to spread their faith.

It was now that the Palatines, the senior line in the Wittelsbach family, made their move. Spotting an opportunity to boost their power, they rallied a significant number of the Protestant princes and cities into a military alliance, called the Union. In response, Duke Maximilian of Bavaria rallied most of the Catholic princes in a rival alliance which was soon dubbed the Catholic League. Though many princes abstained from joining either organisation – and neither side possessed permanent armies – the stakes had been raised significantly.

The Defenestration of Prague is often described as the event that triggered armed conflict. What happened here?

The Habsburgs viewed the Protestant Union as a direct challenge to their authority and, determined to defend their Catholic faith, began restricting court and military appointments to Catholics. This was too much for around 30 Bohemian Protestant nobles to stomach. On the back foot and, in some cases, having recently lost lucrative court jobs, they burst into the government offices in Prague Castle on 23 May 1618. Most of the councillors were absent, but two were quickly thrown out of the window, shortly followed by their secretary. Despite some injuries, all three survived the fall, and the secretary – who had, amazingly, landed on his feet – was able to escape to warn the authorities in Vienna.

A painting shows Protestant nobles throwing two councillors and a secretary out of a window of Prague Castle in May 1618
A painting shows Protestant nobles throwing two councillors and a secretary out of a window of Prague Castle in May 1618. The so-called Defenestration of Prague was the spark that triggered the slide into open war. (Photo by Christophe Boisvieux/Corbis via Getty Images)

The great irony of this incident is that, in 1618, neither side wanted war or had the means to fight. But following the Defenestration, they started arming and calling for support – a move that would have huge ramifications for the future of Europe.

What impact did the personalities of the rival leaders have on the opening exchanges of the war?

A major one – especially in the case of Habsburg leader Ferdinand II, who was crowned Holy Roman Emperor in 1619. Ferdinand was a Catholic hardliner, who as a young man had refrained from drinking and, to quell carnal urges, wore a hairshirt prior to his marriage. He extended this severe attitude to his Protestant foes, interpreting the conflict as a rebellion rather than civil war. As rebels, his opponents had, he believed, forfeited their rights, and he felt free to expropriate them once he had defeated them.

Ferdinand soon canvassed the support of Duke Maximilian of Bavaria and most of the Catholic ecclesiastical princes. Saxony, the most powerful of all the Protestant principalities, also sided with him because it feared that the Union would polarise imperial politics – proof that the two sides did not divide neatly along religious lines.

The Bohemian leadership, meanwhile, formally deposed the Habsburgs and elected Frederick of the Palatinate their king. Frederick was an ambitious, obstinate man, who was convinced by the righteousness of his cause and who had an unshakable belief in ultimate Protestant victory. Unfortunately, he was crowned under a new constitution that deprived the monarchy of most of its power. As he would discover when Ferdinand’s forces fell upon his army at the battle of the White Mountain near Prague on 8 November 1620, he had been handed a poisoned chalice.

The battle of the White Mountain saw Ferdinand’s army rout Frederick’s Protestant coalition before sacking the Bohemian capital of Prague, the victorious troops breaking into homes and robbing with violence. “Those who have nothing, fear for their necks, and all regret not taking up arms and fighting to the last man,” was a contemporary Berlin newspaper’s take on events.

The Habsburgs claimed the White Mountain as a victory for progress; for the Czechs, it ushered in an ‘age of darkness’. Either way, Ferdinand had secured the most important victory of the entire conflict. With his enemy Frederick fleeing to the Dutch Republic, he was now in a dominant position.

What was the conflict like for civilians living in the warzone?

From the massacre of up to 2,000 residents of the town of Münden in Lower Saxony by Catholic forces, to the killing of 154 civilians in Landsberg on the Lech (modern-day south Germany) by Swedes, the Thirty Years’ War was pockmarked by extreme violence against innocent men, women and children.

It’s little wonder, then, that fear is the emotion that leaps out of the pages of contemporary letters and diaries. All were desperate for news and expressed a heavy sense of dread at reports of troops heading in their direction. Maria Anna Junius, a Dominican nun living in a convent on the outskirts of Bamberg – whose father had been executed during the conflict – was one of many to wrestle with the dilemma of whether to flee from advancing Swedish troops. She’d heard of blood flowing down the walls of neighbouring Würzburg, and writes of not being able to sleep for “great fear and anxiety” when the soldiers helped themselves to vegetables in the convent garden.

Virtually any idea that anyone might have had initially that this was a war of religion disappeared once they encountered soldiers who usually behaved equally badly, regardless of which faith they espoused or prince they served. Why was their behaviour so appalling? Primarily because none of the belligerents could pay their soldiers properly, forcing them to live off the land. The war became a constant struggle for survival – especially once it became general across the empire after 1631 – and most commanders were simply unable to curb their troops’ plundering.

The bloodshed, the perpetual fear, the chronic instability manifested itself in other ways. In the Mecklenburg region of northern Germany, entire populations fled to the woods, marshes or lakes. The population of Strasbourg doubled to 60,000 in March 1636 as refugees flooded into the city to escape the carnage. Meanwhile, fear of witchcraft surged in the early 17th century (three escalating waves of persecution in Bamberg probably claimed a thousand victims).

The perception of the Thirty Years’ War as a time of relentless, random slaughter was fostered at the time by the authorities themselves, who presented the war as a divine punishment for the population’s sins. It therefore entered the popular memory as something truly awful that must never be allowed to return.

Why did the war drag on for 30 years?

Ferdinand’s refusal to offer sufficient concessions to his vanquished foes certainly contributed to the war’s longevity. Within a few months of the battle of the White Mountain, the Holy Roman Emperor had seized rebel properties amounting to around half of all landed estates in Bohemia and redistributed these to his supporters. He would repeat this practice with every successive imperial victory.

The trouble was, the defeated Palatines had powerful supporters beyond the boundaries of the Holy Roman Empire. Provoked by Ferdinand’s land grabs – and acting out of naked opportunism – they intervened in the Thirty Years’ War in succession. First Denmark from 1625–29; then Sweden from 1630; and finally France after 1635.

Of these, the Swedish intervention, led by Gustavus Adolphus, is surely the best known. Gustavus is one of the most charismatic figures of the 17th century, whom later generations have, with considerable exaggeration, celebrated as a brilliant military innovator. The British military theorist

BH Liddell Hart even called him the “founder of modern war”. Such awe is, in no small part, due to his exploits at the battle of Breitenfeld in 1631 when his Protestant army inflicted the first major defeat on Catholic forces in the entire war. It truly was a spectacular victory. But when Gustavus was killed in the battle of Lützen the following year, Sweden found itself mired in a seemingly unwinnable war.

Both the emperor and Sweden sustained their war effort by distributing captured land to their German supporters. This added to the difficulties of peacemaking, because neither party felt able to compel their allies to return these gains as part of some compromise peace, yet neither side was strong enough to secure the outright victory needed to dictate terms. So the war continued.

Did the Thirty Years' War have much of an impact on Britain?

Britain’s Stuart monarchy was indirectly involved in the conflict – principally because Frederick was married to Elizabeth, daughter of James VI and I of Scotland and England. When Frederick accepted the Bohemian rebels’ offer of their kingdom’s crown, the couple expected James to back them to the hilt. But the Stuart king – who had declared himself “most afflicted” when his son-in-law failed to ask his advice before accepting the rebels’ offer – refused.

This was a hugely controversial decision – one that would have bloody consequences for the British Isles later in the century. Huge numbers of James’s subjects – many of whom looked back nostalgically to the ‘golden era’ of Elizabeth I’s reign when the English stood up to the Spanish Armada – were enraged by their king’s decision not to back the ‘Protestant Cause’. The Stuarts’ inability to do anything meaningful to restore Frederick and Elizabeth became one of the many popular grudges against their rule that erupted in Britain’s own ruinous civil war.

This disaffection with James’s refusal to help is reflected in the number of Britons – around 113,000 – who joined anti-Habsburg armies during the Thirty Years’ War, notably those of Denmark and Sweden.

Why did the Thirty Years' War finally come to an end?

The war did not end through mutual exhaustion, as is widely thought – France and Spain were able to continue their own, separate conflict for another 11 years! The simple answer is that the key belligerents all came to believe that continued fighting endangered the gains they had already made, and that it was better to settle for these and to end the destruction.

A turning point came in February 1637, when the intransigent Ferdinand II died and was replaced by his son, also called Ferdinand. Ferdinand III was more moderate and willing to compromise than his father. By the early 1640s, the fighting was increasingly centred on securing local advantages intended to strengthen each party’s bargaining position. What’s more, by 1645 it had become obvious that the tide of the war had shifted significantly against the Habsburgs – and the pragmatic Ferdinand III made sufficient concessions to persuade France and Sweden to negotiate. The result was the Peace of Westphalia, which ended the conflict in 1648.

What were the main legacies of the Thirty Years' War?

The Peace of Westphalia defused religion’s potential to polarise politics. The imperial constitution was adjusted, for instance by granting Calvinists equal rights with Catholics and Lutherans. But the most significant change was to entangle the new rights so deeply in the empire’s legal structure that disputes now focused on local problems, rather than big, abstract questions. It was now much more difficult to polarise opinion along religious lines – as Frederick the Great found during the Seven Years’ War (1756–63) when few believed his claims that it was a struggle between Protestants and Catholics, rather than between Prussia and Austria.

In other respects the war was truly a disaster. Large swathes of the empire remained wasteland for decades, pockmarked by burned-out farms and hamlets. Some areas recovered quickly, as did some economic sectors like brewing, since grain was easier to cultivate than grapes, where vineyards had been destroyed. The loss of population also created opportunities for the survivors; for example, land prices crashed, while wages rose. But the overall impression remained one of misery, reinforced by poets and writers who wrote of the “tears of the fatherland”, and a once-flourishing land left waste.

The war occupies a place in German and Czech history similar to that of the civil wars in Britain, Spain and the United States, and the revolutions in France and Russia: a defining moment of national trauma. For most Germans, the war came to symbolise national humiliation, condemning their country to two centuries of internal division and international impotence. It truly was a European apocalypse.


How a religious dispute convulsed central Europe


The Peace of Augsburg grants equal legal protection to Lutherans as well as Catholics in the Holy Roman Empire. These rights extend to all the secular principalities, counties and cities, but the position of the individually small, but numerous church lands are unchanged.


A minority of discontented princes – led by Frederick IV, the Elector Palatine – form the Protestant Union. Duke Maximilian of Bavaria responds in 1609 with the Catholic League as imperial politics polarise over religious and constitutional issues.


In the so-called Defenestration of Prague, a radical group of Bohemian Protestant nobles throw two councillors and a secretary out of the window of Prague Castle. They are denounced as rebels by the ruling Catholic Habsburgs. Both sides begin arming.


Ferdinand II becomes emperor and is backed by Bavaria and Saxony, as well as Spanish and papal financial and military assistance. England, the Dutch Republic and others send money and volunteers but otherwise refuse to support the rebels who are decisively defeated at White Mountain (1620).


Having defeated his opponents, Ferdinand redistributes their lands and titles to his supporters. Denmark believes the changed political balance in the empire threatens its influence in northern Germany and so launches an invasion in 1625. Imperial forces headed by Albrecht von Wallenstein defeat Denmark by 1629.


Ferdinand secures lasting peace with Denmark through generous terms but overreaches himself in the empire by unilaterally issuing the Edict of Restitution, imposing a narrowly Catholic interpretation of the Peace of Augsburg.


Sweden sees Denmark's defeat as an opportunity to expand its influence in the Baltic and to prevent Ferdinand from aiding Poland, its other long-standing enemy. The Swedish invasion restarts the war, but Gustavus Adolphus is unable to advance south.


The sack of Magdeburg by Count Tilly's troops is exploited by Swedish propaganda, but it is not until after Gustavus's convincing victory at Breitenfeld that German Protestant princes join him, largely in the hope of conquering the Catholic church lands.


Ferdinand capitalises on victory at Nördlingen in 1634 to make peace with Protestant principalities but his hardline Catholicism dissuades him from offering sufficient concessions to end the war. France intervenes militarily to prevent Sweden's collapse.


Peace talks open in the Westphalian towns of Münster and Osnabrück in 1643, while each side fights on to improve its bargaining position. The Peace of Westphalia ends the Thirty Years' War in 1648.

Peter H Wilson is Chichele professor of the history of war, University of Oxford. His latest book is Lützen (Oxford University Press, 2018)

BOOK: Europe's Tragedy: A New History of the Thirty Years War by Peter H Wilson (Penguin, 2010)

LISTEN AGAIN: Misha Glenny explored the Thirty Years' War in the opening episode of BBC Radio 4's The Invention of Germany


This article was first published in the June 2018 edition of BBC History Magazine