The Thirty Years War (1618-48)

Fact File

Date: 23 May 1618 – 15 May 1648
Location: Europe
Death Toll: 8 million people, including 20% of the German population
“Reason”: Conflict between the European Catholic and Protestant states. A religious war which developed into a case of a continental power-struggle between most of the states and rulers of Europe
Notable People: Ferdinand II; Frederick V; Philip III; Louis XIII; Cardinal Richelieu; Gustavus Adolphus; Philip IV; Duc d’Enghien; Louis XIV
Notable Battles: Battle of White Mountain (1620); Battle of Breitenfeld (1631); Battle of Lützen (1632); Battle of Rocroi (1643)
Notable Events: Defenestration of Prague (1618); Deposition of Ferdinand II as King of Bohemia (1619); the Edict of Restitution (1629); the Treaty of Lübeck (1629); the Treaty of Barwälde (1631); the Peace of Westphalia (1648).
***NOTE*** I have put a ‘Glossary’ at the end of the post, in case there are any terms you are unfamiliar with. These terms are highlighted in bold throughout.


As with most major historical conflicts, it is almost impossible to pinpoint the exact moment when – or why – a war started. For example, did Franz Ferdinand’s assassination kickstart the First World War? Or was it more a case of increasing imperialism throughout European nations in the early twentieth century which ultimately led to increased ideas and rhetoric of nationalism?

We can also ask the same questions about the Thirty Years War. Was it the succession of the Habsburg Ferdinand II as King of Bohemia in 1617, or was it the Defenestration of Prague the following year, or was it because of Frederick V’s response in 1619? Either way, pinpointing the very start of the Thirty Years War is difficult, but I will try and do my best regardless!

On the Road to Ruin: The Beginning(s) of the Thirty Years War

In 1617, thanks to King Matthias of Bohemia’s actions against religious revolt, Augsburg fell apart. The Bohemian Crown was handed to a Jesuit-trained member of the infamous Habsburg family: Ferdinand II (r. 1617-37), who also became Holy Roman Emperor in 1619. Historian Simon Jenkins states that “no succession could have been more disastrous for Europe.”

Ferdinand undoubtedly shared the military enthusiasm of his cousin, Philip III of Spain (r. 1598-1621), but whereas the majority of Philip’s subjects were Catholic, the majority of Ferdinand’s Bohemian subjects were Protestant. In Spring 1618, news reached Prague (then the capital of Bohemia) that Ferdinand intended to replace Bohemia’s Protestant governors with Catholics: this resulted in immediate revolt, and most famously, the Defenestration of Prague on 23 May 1618.

No succession could have been for disastrous for Europe.

Historian Simon Jenkins on Ferdinand II becoming Holy Roman Emperor in 1619
Ferdinand II (r. 1617-37)

The Defenestration of Prague

Upon hearing the news about Ferdinand replacing Bohemia’s Protestant governors with Catholic ones, a delegation of Protestant Bohemian nobles entered the Hradčany Castle in Prague on 23 May 1618 and threw two Habsburg governors (Jaroslav von Martinitz and Wilhem von Salvata) out of a sixth-storey window and into a dung heap – which actually broke their fall. Ironically, both von Martinitz and von Salvata were protesting against recent attacks on Protestant churches, against Ferdinand’s assumption of the Bohemian throne, and against his alleged violations of the Royal Charter of Toleration (the Majestätsbrief) of 1609. This Defenstration of Prague was a deliberate imitation of an incident almost two centuries before, when seven members of the Prague city council were killed by a crowd of Czech Hussites in 1419, which lit the spark for the Hussite Wars to ignite.

The Defenestration of Prague, 23 May 1618

The Bohemian Response and Frederick V

At the time of the Defenestration of Prague, Ferdinand was campaigning for the imperial election (the election for Holy Roman Emperor), and religious peace in Germany was faltering. The Lutheran princes were awkwardly watching as the newly formed Protestant Union led by Frederick, Elector Palatine, squared up to the Catholic League, led by Maximilian, Elector of Bavaria. Eventually the religious tension cord snapped, and the Bohemian rebels invaded Vienna, prompting a revolt in Austria. In 1619, upon Ferdinand’s successful succession to the imperial throne, the Bohemians formally deposed him as King of Bohemia, instead electing the Calvinist Frederick in his place. This, in simple terms, meant open war.

Frederick V (r. 1610-23)

Frederick, the Elector Palatine of a small Rhineland state became Frederick V of Bohemia, in Ferdinand’s place. As I mentioned earlier, Frederick was a Calvinist, and he was married to Elizabeth Stuart, daughter of King James I of England. Dubbed the ‘jewel of Europe’, she was soon to become a lasting object of Protestant adoration.

In response, Ferdinand summoned Catholic monarchs and mercenaries from across Europe to wage a war of faith on what he viewed as his Protestant subjects. Spain (under Philip III), Poland (under Sigismund III), and the Papacy (under Pope Paul V), all joined Ferdinand in a Catholic League, which Jenkins refers to as ‘an intra-European crusader force.’

On the other hand, Frederick was backed by Dutch Protestants, Scandinavians, the French (deviously, under Louis XIII) and the English (half-heartedly, under James I). The ensuing conflict retracted the values of the Peace of Augsburg* and showed how far one man’s faith could dictate the fate of nations.

*The Peace of Augsburg was signed by the then Holy Roman Emperor Charles V, and the Schmalkaldic League in September 1555. It officially ended the religious struggle between the two aforementioned groups and made the legal division of Christianity permanent within the Holy Roman Empire, allowing rulers to choose either Lutheranism or Roman Catholicism as the official confession of their state.

Open War: The Battle of White Mountain (1620)

On 7 November 1620, just outside Prague, Ferdinand’s Catholic forces and Frederick’s Protestant forces met on the battlefield for what was to become the first open fielded battle of the Thirty Years War.

Frederick’s Protestant forces were soundly defeated by Ferdinand’s Catholic forces, and the consequences were huge. Ferdinand reacted to his victory with brutality and had 27 Bohemian leaders executed in Prague’s Old Town Square. All of Bohemia’s Non-Catholic nobles had their lands confiscated, and all Protestants were evicted, the majority of whom fled west into Germany. The Catholicisation and Germanisation of Bohemia had begun. This religious cleansing in Bohemia was so successful that to this day, Bohemia remains largely Catholic.

The Battle of White Mountain, 7 November 1620. The first pitched battle of the Thirty Years War.

Frederick fled, and along with his wife Elizabeth, they both became refugees in The Hague, known for the shortness of their one-year reign as the “Winter King and Queen”. After Frederick and Elizabeth fled, their lands in the Palatine were invaded by the Spanish Netherlands and seized by the Bavarians. The General of the Catholic Forces, Count Tilly (1559-1632), stormed Heidelberg in 1622 and traversed northern Germany in pursuit of the Protestant forces held by Count von Mansfeld (1580-1626).

Pressure from the North: Scandinavian Involvement (c. 1620-35)


While Count Tilly was ravaging northern Germany, Ferdinand discovered a major problem about using mercenaries in his army: he found that he could not pay them enough, as he had run out of money. The fighting became almost like banditry, and as a result, all of Europe was dragged into it: including Denmark and Sweden.

By the early 1620s, after the Battle of White Mountain, Christian IV of Denmark, Superior of the Imperial Circle of Lower Saxony, entered the conflict in defence of his hard-pressed Protestant confreres. He had to contend with a new imperialist army raised by a Bohemian Catholic nobleman: Albrecht von Waldstein, or more commonly known as, Albrecht von Wallenstein (1584-1634).

The Protestant forces (which included forces from England, France and the Netherlands) were defeated again at the Bridge of Dessau on the River Elbe in 1626, and Count von Mansfeld’s Protestant forces (whom Count Tilly had pursued since 1622) were defeated at Neuhausel, near Bratislava (capital of modern-day Slovakia). Count Tilly then attacked the Protestant Netherlands with help from the Spanish under Philip III.

Meanwhile, Wallenstein overran the majority of the lands on the Baltic Coast: Brunswick, Lower Saxony, Mecklenburg, Schleswig, Holstein, Jutland and the Baltic Coast to the outskirts of Stralsund, declaring himself ‘Generalissimo of the Baltic and the Ocean Seas’.

By the Edict of Restitution (6 March 1629), Ferdinand ordered the Protestants to surrender all the former Ecclesiastical lands acquired since the Peace of Augsburg. Interestingly, Wallenstein objected, because his army contained many non-Catholics. He was then dismissed. Finally, the Treaty of Lübeck (22 May 1629), was signed by Wallenstein, Christian IV and Ferdinand II, which ended Danish involvement in the Thirty Years War by persuading them to retire on the return of their lost possessions. The deal was a winner for everyone involved in the signing of the treaty. However, the war was far from over yet.


Sweden entered the fray shortly after Denmark had signed the Treaty of Lübeck. Gustavus Adolphus, also known as Gustav II of Sweden (r. 1611-32), sent a contingent to hold Stralsund in northern Germany. Fortified by the Treaty of Bärwalde (signed on 23 January 1631, which was an agreement by France to provide Sweden with financial support following its intervention in the Thirty Years War), Gustavus landed in Germany with the main Swedish army and proceeded to vigorously restore Protestant fortunes. The reason behind this treaty was largely thanks to the Catholic King Louis XIII of France and his adviser Cardinal Richelieu, as they followed French policy in siding with any foe of a Habsburg (essentially, their philosophy was my enemy’s enemy is my friend), even a Protestant one. Hence King James I of England, a Protestant, even sent a small army of soldiers to the continent to support Louis XIII and Gustavus’ treaty.

Gustavus Adolphus (r. 1611-32)

However, the campaign did not get off to a strong start. Gustavus failed to relieve Magdeburg before it was mercilessly sacked by the imperialists, but at the Battle of Breitenfeld (17 September 1631), he crushed Tilly, and moved into the Palatinate. In 1632, Gustavus entered Bavaria, and Munich and Nuremberg opened their gates to his forces. The Swedish army planned to move on to Vienna later in the year, so Ferdinand was forced to recall Wallenstein, after he had previously dismissed him after his objection towards the Edict of Restitution three years before.

The Sack of Magdeburg (20 May 1631) is often regarded as the worst massacre of the Thirty Years War. It is sometimes referred to as the ‘Rape of Germany’.

The next major battle was the Battle of Lützen, just over a year after Breitenfeld, on 16 November 1632. It was a furious battle, and although the Swedish forces prevailed, Gustavus fell. He was found under a heap of dead bodies, with bullet holes in his head and a dagger thrust into his side. Similarly, following an infection from a wound, Frederick V died on 29 November. These two catastrophes, less than a fortnight apart, dashed any hopes the Protestants had of an early end to the conflict.

The Western Sphere: French Involvement (c. 1635-48)

Concerned that Philip IV of Spain (r. 1621-65), would use the war to reunite Charles V’s Spanish and Austrian Habsburg Empires, in 1635 Louis XIII and Richelieu officially declared war on Spain. At this point, it was not just Catholic versus Protestant, but Catholic Bourbon versus Catholic Habsburg. France once more took the Swedish forces into their pay, and invaded Alsace.

Cardinal Richelieu (1585-1642)

In 1636, Spanish forces reached the outskirts of Paris, but they soon understood how it could be a disadvantage having territory stationed throughout Europe, when the French threatened Spanish Flanders, and sent reinforcements to the Swedes in the north. The Protestants even invited the Ottoman Turks to attack Austria from the East. “Europe was in turmoil.”

A year later, in 1637, Ferdinand II died, which initially raised hopes for an eventual peace. However, by this point, the war already had a momentum of its own. The war was no longer religious back in Germany – as mentioned earlier, undisciplined mercenary troops tore principalities apart and created conflict where there previously was none before. 

However, by 1638, French fortunes were mounting: the rise of the youthful Duc d’Enghein (Louis II, Prince de Condé, 1621-86), who was referred to by contemporary chroniclers as ‘the finest general in Europe’, helped improve morale in the French forces.

The Battle of Rocroi (19 May 1643) was the final pitched battle of the Thirty Years War. Yet it was to be another five years before the war officially ended.

Aged just 21, the Duc d’Enghein took to the battlefield at Rocroi in the Ardennes against a Flemish army on 19 May 1643, and roundly crushed the tercios (a Spanish infantry unit) and ended Spanish participation in the war, as well as Spanish military supremacy in Pavia, which had lasted since 1525. Rocroi was also the final pitched battle of the Thirty Years War. This dynastic conflict between France and Spain from 1635 resulted in Louis XIV of France (r. 1643-1715) making peace in 1648, coming about as a belief that the Habsburgs were too powerful.

The End in Sight: The Peace of Westphalia (1648)

In 1643, in the immediate aftermath of Rocroi, diplomats from all parties represented (109 diplomats in total) met in two separate towns in Westphalia: Osnabrück and Münster. Emissaries scuttled back and forth between the sides, reaching not just one treaty, but also a series of local deals designed to roll into a collective peace. The agreement took five years, and was eventually signed on 15 May 1648, finally bringing about a formal end to the Thirty Years War.

A painting of the Peace of Westphalia, the treaty which formally ended the Thirty Years War on 15 May 1648.

But how did this particular treaty manage this, and what were the main details of it?

It was, essentially, a reversion to Augsburg – a principle of national self-determination in politics and faith. Westphalia restored the autonomy of the German states and denied authority over them to the Holy Roman Empire. In fact, some historians even argue that Westphalia is credited with fathering the concept of the nation state. In addition, Westphalia formally accepted the reality of a Europe that had fought itself to exhaustion.

On the religious issue – which is what the war started out as in the first place – it granted the same rights to Calvinists as it did to Lutherans and Catholics, in Germany. On the constitutional issue – which the war had evolved into throughout the 1630s – it greatly strengthened the European Princes, by granting them the right to sign foreign treaties by making all imperial legislation conditional on the Diet’s approval.


German manufacturing and trade collapsed, while sowing and harvesting ceased. Estimates from a third to a half of 20 million German speakers died. A notable example is in Magdeburg, which had 20,000 inhabitants in 1620, and 450 in 1649. France gained land deep into Germany, in Alsace and the Rhine basin. Germany itself was left ruined, and it took over a century for it to recover.

Everything has been razed to the ground and hardly a soul can be seen…

A Swedish General describing the scenes between Prague and Vienna

Further north, Sweden arose as a northern European powerhouse, gaining some north German territories along the way.

In South-West Europe, Spain was also left a shattered realm, decoupled forever from the Holy Roman Empire.

In Bohemia, a Swedish general wrote home saying that ‘I did not expect to find the kingdom so lean, wasted and spoiled, for between Prague and Vienna, everything has been razed to the ground and hardly a living soul can be seen on the land.’

One of the few prosperous countries to emerge was Protestant Prussia. Under the leadership of the Hohenzollern family of the ‘Great Elector’ Friedrich Wilhem (r. 1640-88).

The thoughts of Pope Innocent X (r. 1644-55) sum up the Papacy’s thoughts on Westphalia (although this is possibly because the Papacy was unrepresented, for obvious reasons), as he denounced it as:

‘null, void, invalid, iniquitous, unjust, damnable, reprobate, inane and devoid of meaning.’

Pope Innocent X on the Peace of Westphalia


The Thirty Years War has been called by some historians a ‘European Civil War’. This is not far from the truth, as almost all of the European states – at some point from 1618-48, were involved, although clearly some were involved more than others. Another reason why this conflict is so significant, and widely remembered on the continent, is because of Johannes Gutenberg’s invention in the fifteenth century: the printing press. Images of tortured civilians were widespread, and thanks to the printing press, actual depictions of the levels and scale of torture could be witnessed by civilians, not just those soldiers actively taking part in the conflict.

A map of battles and territories won and lost during the Thirty Years War.

Historian Norman Davies argues that the Thirty Years War can be seen as an age-old German conflict between Emperors and princes, but that it can also be seen as “an extension of the international wars of religion between Catholic and Protestant, as an important stage in a Continental power struggle involving most of the states and rulers of Europe.” Personally, I am inclined to agree with this: that it initially started out as a war of religion, and eventually developed into the aforementioned power struggle.

Thus, a suitable conclusion would be to turn to the words of acclaimed historian of the Thirty Years War, Veronica Wedgwood, who summarised thirty years of conflict in two sentences: “[The combatants] wanted peace and they fought for thirty years to be sure of it. They did not learn then, and have not learned since, that war only breeds war.”

Thanks for reading!

For more of my other work, please check out my author profile at The Collector here.


I thought that a sort-of ‘glossary’ might help to consolidate some of the terms/families used within this post.

Bavaria: During the Thirty Years War, the Electorate of Bavaria was an independent electorate of the Holy Roman Empire.
Bohemia: A kingdom in the Holy Roman Empire which covered the majority of the modern-day Czech Republic.
Calvinist: A major branch of Protestantism which follows the teachings of a French preacher, John Calvin (1509-64).
Defenestration: the act of, literally, throwing someone out of a window.
Diet: The General Assembly of the Imperial Estates of the Holy Roman Empire.
Elector Palatine/Palatinate: A territory in the Holy Roman Empire whose rulers served as prince-electors of the Empire.
Habsburg: One of the major European royal houses, who continuously occupied the throne of the Holy Roman Empire from 1440 until 1740, and again from 1765 until its dissolution in 1806.
Holy Roman Empire: A multi-ethnic complex of territories in Western and Central Europe which was considered by the Catholic Church as the only legal successor of the Roman Empire during the Middle Ages and the Early Modern period.
Jesuit: A religious division of evangelical missionary Christianity, founded on the approval of Pope Paul III in 1540.
Lutheran: Another major branch of Protestantism, which follows the teachings of the Reformer Martin Luther (1483-1546).


Norman Davies, Europe: A History (2014)
Simon Jenkins, A Short History of Europe (2018)
John Julius Norwich, The Popes: A History (2011)
Eduard Wagner, European Weapons and Warfare 1618 – 1648 (2014)


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