below Gustavus Adolphus, the Swedish king, at the Battle of Breitenfeld, 17 September 1631, the first major Protestant victory of the Thirty Years’ War. Painted by Johann Walter (1594-1634).

The Thirty Years’ War: 1618-1648

Stephen Roberts traces the history of the Thirty Years’ War, Europe’s most destructive conflict prior to the First World War.


Before the First World War, it was known as the most destructive conflict in European history – responsible for the loss of as much as 40 per cent of the German population, which according to some estimates may have fallen in the years between 1618 and 1648 from around 20 million to 12 million. This immense human toll as a result of battle, famine, and disease would scar the continent for centuries – so that some historians describe it as the greatest trauma in German history.

But as well as being horrific in terms of the sheer numbers of casualties inflicted and lives destroyed, the Thirty Years’ War was also horrific for the manner in which it was conducted. As the large number of surviving eyewitness accounts attest, this was a war of attrition, in which civilians often found themselves on the front line. Massacres such as that during the Sack of Magdeburg – the conflict’s worst atrocity, which left up to 20,000 of the city’s 25,000 Protestant inhabitants dead – were conducted without mercy. Huge numbers of refugees were also created, as neighbours were pitched against each other, and entire areas of the country were laid waste.

It began as a local dispute – over the zealous anti-Protestant policies introduced by Ferdinand of Styria (the future Holy Roman Emperor Ferdinand II), who in 1617 was elected as the new king of Bohemia (the modern-day Czech Republic). Protest sparked into war following the momentous event known as the Defenestration of Prague, on 23 May 1618, when a group of local noblemen threw two of Ferdinand’s newly appointed Catholic governors from a high window at Prague’s Hradcany Castle. Over the next three decades, the conflict escalated to become Europe’s apocalypse – fought out over four distinct phases that can on one level be seen as part of the wars of religion between Catholics and Protestants, but on another as part of a more complex international struggle that would eventually pull in most of Europe’s great powers.

With the benefit of hindsight, the Thirty Years’ War is often described as the first modern conflict: a military revolution involving entire populations and whole economies, and ushering in a new age of total warfare that, as the historian Michael Roberts noted in an oft-quoted article published in 1956, stands ‘like a great divide separating medieval society from the modern world’. More recently, attempts have been made to draw parallels between the various interconnected religious and sectarian struggles fought out during the Thirty Years’ War and those that now divide the Middle East.

As we discover over the following pages, however, such observations would be lost on the millions who lived and died during the course of this epochal conflict, as central Europe was smashed to pieces around them. In our two-part special for this issue, Stephen Roberts first offers an overview of the long and painful history of the war; and then analyses in detail the Battle of Lützen, the crucial engagement on 16 November 1632 that cost the life of a king.

Gustavus Adolphus, the Swedish king, at the Battle of Breitenfeld, 17 September 1631, the first major Protestant victory of the Thirty Years’ War. Painted by Johann Walter (1594-1634).

A new way of war?

A decade or so ago, when I wrote a cover story for MHM on Edward III (January 2013), I pondered whether the English king had instituted a new kind of warfare during the Hundred Years’ War. One hundred and sixty-five years after that long-running conflict between England and France had ended, another contest defined by its duration, the Thirty Years’ War (1618-48), began. Europe’s most destructive conflict prior to World War I, it would decimate much of the Holy Roman Empire, spreading through Italy, France, Spain, and the Netherlands. Here, I will tell the war’s story – but I must also pose the same question: was this a new way of fighting?

The Thirty Years’ War is usually divided into four periods. The first two phases, known as the ‘Bohemian’ and ‘Danish’ periods, were mainly religious in character – developing from a Protestant revolt against Catholic rule in Bohemia (the medieval and early modern predecessor to the modern Czech Republic) into a more general conflict between German Catholics and Protestants. The last two, known as the ‘Swedish’ and ‘Swedish-French’ periods, were more political – directed against the power of the Austrian Habsburg rulers of the Holy Roman Empire, who sought to extend their European control. These were Swedish-French wars of conquest fought on German soil as Protestant powers (Sweden/Denmark) and Protestant German princes, aided by Catholic France (after 1635), sought to keep the Habsburg genie bottled.

The key figure in the war’s genesis was Ferdinand of Styria – the future Holy Roman Emperor Ferdinand II – who in 1617 was elected King of Bohemia. Jesuit educated, the zealous Ferdinand vowed to eradicate heresy from his patrimonial lands and was against honouring privileges granted to the majority Protestant population by his predecessor, Emperor Rudolf II (in the Letter of Majesty, 1609). For Ferdinand, any whiff of Protestant equality in Bohemia was anathema.

The Battle of White Mountain, fought outside Prague on 8 November 1620, led to the suppression of the Bohemian revolt in the early stages of the war.

1618-25: The Bohemian period

For a war of such length and destructive magnitude, it began obscurely – with the closing of a Protestant church, the destruction of another, and the installing of a Catholic-dominated administration following Ferdinand’s election. This led to a Protestant revolt in Prague, led by Bohemian nobleman Count Matthias von Thurn. On 23 May 1618, the notorious event known as the Defenestration of Prague effectively detonated the war, when a group of armed protesters chucked two of Ferdinand’s newly appointed Catholic governors and their secretary from a 70-foot-high window at Prague Castle; miraculously, they survived – though it is said that was only because of a build-up of dung in the ditch below. The rebels appointed directors to form a provisional government, gained reinforcements in the form of mercenaries recruited by the Duke of Savoy and commanded by Count Ernst von Mansfeld, and set about the defeat of Imperial forces. The first major military event was the Siege of Pilsen, in eastern Bohemia, which had stayed loyal to the Emperor; after several weeks, it fell to Mansfeld on 21 November 1618

The following year, Thurn made an early attempt on the Habsburg capital of Vienna, abandoned on 14 June. On 19 August 1619, the Bohemians deposed Ferdinand II from their throne, just nine days before he was elected Holy Roman Emperor (the timing mattered, as the rebels claimed they’d merely deposed an Austrian archduke). Elected as Bohemian king in his place was Frederick V of the Palatinate (also known as Rhenish Bavaria), the son-in-law of England’s James I – a familial connection that did not benefit the Protestants, as England remained effectively neutral with James preferring to play ‘honest broker’ (partly because he was pursuing the Spanish infanta for his son). Thurn stalked Vienna again, this time with Bethlen Gabor, Prince of Transylvania, but a retreat ensued: Gabor was bought off by the Imperialists with an offer of a nine-month truce.

The key figure in the war’s genesis was Ferdinand of Styria, the future Holy Roman Emperor Ferdinand II. Elected King of Bohemia in 1617, he vowed to eradicate heresy from his homeland.

Ferdinand had powerful allies – including the Papacy, a natural bedfellow. Via the Treaty of Munich, signed on 8 October 1619, he formed a tripartite alliance with Maximilian I, the Duke of Bavaria (and head of the Catholic League), and Spain. A separate ‘unholy alliance’ with John George, the Lutheran Elector of Saxony, showed this was not simply a Catholic versus Protestant contest, but one that was also Lutheran (Saxony) versus Calvinist (Bohemia). That division between Lutheran and Calvinist was almost fatal for the Protestant cause in Germany, and was aided by the Treaty of Ulm (3 July 1620) between Ferdinand and France, which gave the Emperor a free hand to suppress his fractious subjects.

Maximilian marched on Bohemia with the Catholic League army commanded by Jan Tserkales, Baron von Tilly, and gained a decisive victory against Frederick V’s troops commanded by Christian of Anhalt at the Battle of the White Mountain (8 November 1620), fought outside Prague. The subjugation of the Bohemians would follow. The Protestant Union was dissolved and the Palatinate conquered. Tilly recovered from defeat at Mingolsheim (April 1622) to achieve victories at Wimpfen (May 1622) and Höchst (June 1622). On 23 February 1623, Maximilian received the electoral vote belonging to Frederick V, effectively deposing him; while on 6 August 1623, Tilly’s victory over Christian of Brunswick, the nephew of Denmark’s King Christian IV, at Stadtlohn, was arguably the most decisive of all Catholic wins to date. With no fighting in Germany in 1624, the first period was over.

With hindsight, many now view the Thirty Years’ War as the first truly modern conflict – ushering in a new age of ‘total war’ (i.e. that involving whole economies and entire populations). But that would have been far from clear during the Bohemian period, which still bore the hallmarks of a small-scale, localised conflict – albeit one dragging on for several years. It also began as a religious conflict – one of the last wars about which that could truly be said; in the future, wars would be more commercial in nature.

1625-29: The Danish period

In this phase, Christian IV, King of Denmark, assumed the Protestant leadership, while the Bohemian soldier and statesman Albrecht von Wallenstein commanded the army of the Holy Roman Empire, defeating Mansfeld at the Bridge of Dessau on 25 April 1626. On 5 August 1626, Tilly overcame Christian IV at Lutter am Barenberge – another Catholic victory, and one which rivals Stadtlohn as Tilly’s finest hour.

In 1627, Tilly and Wallenstein combined to conquer Danish Holstein whilst Wallenstein also subdued nearby Schleswig and Jutland. In 1628, Wallenstein besieged the Baltic city of Stralsund, where a heroic ten-week defence forced him to raise the siege – but this didn’t stop Christian IV’s withdrawal from the war. It’s just conceivable the conflict could have ended here had Ferdinand been satisfied with the gains made. Instead, the Emperor issued the Edict of Restitution (on 29 March 1629), designed to restore ecclesiastical estates and suppress the free exercise of religion – which basically meant stuffing the Calvinists. Wallenstein’s troops and those of the League enthusiastically executed the edict. On 22 May 1629, the Treaty of Lubeck was agreed between the Emperor and Christian IV, who swore not to interfere in German affairs, abandoning his allies, while the Dukes of Mecklenburg (in northern Germany) lost their lands to Wallenstein for having supported the Danish king.

With the second phase now coming to an end, it was already possible to say that the Thirty Years’ War was making waves. Contemporaries reported not only the horrors of the fighting but also the sufferings of civilian populations as the terrorising of those not at the front became part of the strategy. Some parts of Germany were plundered repeatedly as armies lived off the land.

1630-35: The Swedish period

The war’s third phase introduced the figure of Gustavus Adolphus, King of Sweden from 1611 to 1632, who landed on the Pomeranian coast (on the southern Baltic shore) with nearly 18,000 troops in July 1630. That he entered the fray now was made possible by his own country’s Polish war having halted in 1629, leaving him free to campaign elsewhere. As well as being wary of the Emperor’s maritime ambitions, his aim was to protect oppressed Protestants, restore the Dukes of Mecklenburg (his relatives), and reject the Treaty of Lubeck.

The Swedish influence was largely responsible for the shifting sands of the Catholic-Protestant military balance from 1630, with Adolphus the third period’s key figure. The aim was a mobile war, the acquisition of land enabling a larger Swedish army to sustain itself; this meant occupying the Emperor’s territories, and forcing him to negotiate. Gustavus already had Finland and Estonia; if he added Prussia and Pomerania, the Baltic would become a Swedish sea. To this end, he drove Imperial forces from Pomerania, and captured Frankfurt an der Oder in the state of Brandenburg, with Spandau also surrendering.

From 20 to 24 May 1631, the capture of the Lower Saxon city of Magdeburg by the Imperial army under Tilly and the forces of the Catholic League saw a terrible massacre: a storm of violence conducted by field marshal Count Gottfried Pappenheim left up to 20,000 of the city’s 25,000 Protestant inhabitants dead – the war’s worst atrocity. Tilly also captured Leipzig but Adolphus crossed the Elbe at Wittenberg – the two armies (of c.40,000 each) meeting at the First Battle of Breitenfeld, just north of Leipzig, on 17 September 1631. The Saxons were initially bested by Tilly – but Adolphus eventually won a brilliant but bloody victory, enabling the Saxons to enter Bohemia. With an estimated 13,600 casualties among Tilly’s forces, against around 5,550 on the Swedish-Saxon side, this set-piece battle was the Protestants’ first major success – after 13 years of war.

On 23 May 1618, the event known as the Defenestration of Prague plunged Bohemia into war, when two of Ferdinand’s newly appointed Catholic governors were thrown from a window at Prague Castle.

Adolphus reached the Rhine, occupying Mainz, while to the east Prague was captured by the Saxons under Hans Georg von Arnim-Boitzenburg. Just when the war had swung the Saxon-Swedish alliance’s way, however, Wallenstein orchestrated a fightback, recapturing Prague and driving the lukewarm Saxons from Bohemia. In 1632, Adolphus advanced to the Danube to meet Tilly, forcing conflict at the Battle of Rain (in Bavaria), where Tilly was mortally wounded. Adolphus then besieged Maximilian at nearby Ingolstadt and forced Munich’s surrender. Between July and September 1632, Adolphus and Wallenstein faced one another for eleven weeks near Nuremberg but the latter, in a fortified camp, refused battle. Reinforced by the ambitious Protestant general Bernhard of Saxe-Weimar, the Swedes finally attacked but were repulsed with heavy losses. Adolphus advanced to the Danube again but Wallenstein turned on a defenceless Saxony, resulting in terrible ravages. Reunited with Bernhard, Adolphus fatefully pursued Wallenstein to Lützen, south-west of Leipzig, where in an epic encounter on 16 November 1632 (covered in detail on p.28) equal forces of 19,000 slogged it out, and both Adolphus and Pappenheim were killed.

The Battle of Stadtlohn on 6 August 1623 was a resounding Catholic victory that marked the end of the first phase of the Thirty Years’ War.

The following year saw growing estrangement between Wallenstein and the Imperial court – leading to a proclamation on 24 January 1634 that Wallenstein had plotted to oust the Emperor. On 25 February, Wallenstein was assassinated by his own officers in Cheb, west of Prague – completing a trio (with Tilly and Pappenheim) of mortal losses among Imperial commanders.

The war’s epicentre now shifted to Bavaria and the Rhineland. There, on 6 September 1634, Imperial forces under Ferdinand (the Emperor’s son – later to succeed his father as Ferdinand III) won a thumping victory over the outnumbered Swedes and Bernhard at Nordlingen, leaving the depleted Franco-Swedish forces to nurse their wounds on the left bank of the Rhine.

The war’s third phase, known as the Swedish period, began when Gustavus Adolphus, the king of Sweden, landed on the Pomeranian coast in July 1630.

Finally in this period, the Treaty of Prague (30 May 1635) was agreed between the now-ailing Emperor and the turncoat Elector of Saxony, which suspended the Edict of Restitution and included an agreement to make common cause against Sweden. With other German states subsequently also defecting, a period which started brightly for Sweden and the Protestants was now ending ominously.

Below: The war’s worst atrocity occurred in May 1631, when the capture of Magdeburg by the Imperial army under Jan Tserkales, Baron von Tilly (above), led to the deaths of up to 20,000 of the city’s 25,000 Protestant inhabitants.

1635-48: The Swedish-French period

Although the Swedish-French phase is reckoned to start in 1635, the two countries had been allies since the signing of the Treaty of Bärwalde in January 1631 – so that year can be argued as the war’s midway hinge, with Adolphus’ victory at Breitenfeld and Sweden/France agreeing to stick it to the Imperialists. It ceased being a German war and became European. Under the control of Cardinal Richelieu, France fought by proxy, using Bernhard as its new ally. In 1638, the Rhineland fortress of Breisach – an important stop on the supply line known as the Spanish Road – was captured, but Bernhard’s death on 11 July 1639 led to France assuming control of his army. Unlike the Swedes, the French never fully committed: their priority was contesting the Low Countries with Spain. However, they were ready to bash the Habsburgs, even supporting Protestants to do it.

On 4 October 1636, the Swedes (under field marshal Johan Banér) were victorious over the Imperialists/Saxons at Wittstock, and in 1637 the death of Ferdinand II left his son, Ferdinand III, desiring peace. In another reversal of fortunes, the disease-ravaged Swedes were by the end of that year barely retaining Pomeranian pockets. On 2 November 1642, the Second Battle of Breitenfeld saw Lennart Torstenson – now the Swedish commander-in-chief following the death of Banér – defeat the Imperialists under the Italian nobleman Ottavio Piccolomini, with Leipzig capitulating within the month. These unexpected Swedish successes threatened the Emperor’s hereditary states, and caused Denmark and Christian IV to be envious.

On 25 February 1634, Albrecht von Wallenstein, the commander of the army of the Holy Roman Empire, was assassinated by his own officers in Cheb, west of Prague.

The war’s embers resembled a slugfest, with much toing and froing as two exhausted boxers tried to get to the end of the final round. During 1643-45, war ensued between Sweden and Denmark, with Torstenson conquering Holstein and Schleswig, and invading Jutland. The French were also surprised at Tuttlingen, on the Danube, by an Austro-Bavarian army and defeated. In 1644, the French forced a Bavarian retreat, while an Imperial army assisted the hard-pressed Danes. In January 1645, an Imperial force was pursued back into Germany and almost obliterated at Magdeburg. On 6 March 1645, Torstenson’s brilliant victory over the Imperialists at Jankau (in Bohemia) – the first time the Swedes had prevailed because of their artillery – saw him advancing on Vienna before vainly laying siege to Brünn, in Moravia.

The Peace of Westphalia, which finally ended the Thirty Years’ War in 1648, left things little different from when it started, despite an estimated 8 million casualties.

Peace followed between Sweden and Denmark. Torstenson resigned his command due to illness (replaced by Wrangel) but in 1646 the Swedes and French united to invade Bavaria, forcing the Elector Maximilian to conclude the Truce of Ulm (1647) and renounce his alliance with the Emperor. Maximilian broke the truce and joined the Emperor once more. In 1648, however, a second invasion of Bavaria by the Swedes/French with awful ravages led to the two treaties, known as the Peace of Westphalia, which finally ended 30 years of conflict.

A New Way of War?

If the Thirty Years War did indeed add up to a new way of conducting warfare, it was one that featured not only more offensive formations generally, and the use of cavalry as shock troops (a refinement rather than revolutionary), but also developments in military schooling, training and the use of training manuals, strategic thinking, and logistics. Intelligence gathering also became more vital. There was increasing professionalism, including using mercenaries; improvements to firearms, such as the muzzle loader; greater standardisation plus improved field craft, with more maps and field glasses; and greater autonomy of command, enabling armies to strike fast rather than wait while orders filtered down.

But why then, if there was this advancement in the way of war, did it drag on for 30 years until the so-called ‘Peace of Exhaustion’? If it was the first modern war, why did neither side achieve a breakthrough? The war became one of attrition, the most devastating of early modern Europe. Even the treaty negotiations dragged on for five years (1643-48), making these the longest in early modern European history – with the fighting persisting all the while.

The full horror of the conflict was brought home by artists such as Jacques Callot, whose series of prints entitled ‘Miseries of War’ was published in 1633. Here, he depicts a mass public hanging, with soldiers gathered beneath the bodies.

The Thirty Years’ War was the first conflict in which civilians regularly found themselves on the front line. There were three reasons for this: the war’s duration; its scale, with larger armies regularly operating; and its ability to sustain itself, with the cost falling on civilians. What happened to Magdeburg is just one example, with the city’s population falling from 20,000 in 1620 to just 450 in 1649.

The way conflict was reported was changing too. The first battlefield photographs lay in the future – but the Thirty Years’ War saw advances in the visual depiction of events courtesy of accurate engravings by the Swiss Matthäus Merian the Elder, who died shortly after the war’s end in 1650, and the contributions of Johann Philipp Abele and Jacques Callot. The war was also written about more graphically – most famously via three novels of Johann Jakob Christoph von Grimmelhausen, published between 1668 and 1670. In fact, with more than 70 eye­witness accounts there were new standards of war reporting. A dramatic, journalistic approach was arguably the start of anti-war prose and pictures.

Further Reading:
• Richard Bonney, The Thirty Years’ War 1618-1648 (Osprey Publishing, 2002).
• Peter H Wilson, Europe’s Tragedy: a new history of the Thirty Years’ War (Penguin, 2010).
• John Pike, The Thirty Years’ War, 1618-1648: the first global war and the end of Habsburg Supremacy (Pen & Sword Military, 2023).

All Images: Wikimedia Commons unless stated
You can read the second part, the analysis of The Battle of Lützen by Stephen Roberts here