What was the Thirty Years’ War (1618-1648)?


The Thirty Years’ War (German: Dreißigjähriger Krieg) was a conflict fought in modern Germany and Central Europe from 1618 to 1648. Estimates of total military and civilian deaths range from 4.5 to 8 million, mostly from disease or starvation. In some areas of Germany, it has been suggested that up to 60% of the population died. Related conflicts include the Eighty Years War (1568-1648), the War of the Mantuan Succession, the Franco-Spanish War, and the Portuguese Restoration War.

Until the mid-20th century, it was seen as predominantly a German civil war and part of the European wars of religion. In 1938, C.V. Wedgwood argued it formed part of a wider European conflict, whose underlying cause was the ongoing contest between Austro-Spanish Habsburgs and French Bourbons. This view is widely accepted by modern historians, although debate continues over the extent to which it was a European rather than German conflict, and the accuracy of the title ‘Thirty Years’.

The war consisted of two main phases, the first being a primarily internal conflict between Emperor Ferdinand II and his opponents within the Holy Roman Empire, with external powers playing a supportive role. Beginning in 1618, this period ended with the Peace of Prague in 1635. In the second phase, fighting in Germany became part of a wider European struggle, with Sweden and France on one side, the Spanish and Austrian Habsburgs on the other. This ended with the 1648 Peace of Westphalia.

Conflict between German Protestants and Catholics caused by the early 16th century Reformation was temporarily settled by the 1555 Peace of Augsburg. This agreement was gradually undermined by political and religious tensions, and in 1618 the Protestant-dominated Bohemian Estates deposed the Catholic Ferdinand II as King of Bohemia. They offered the Crown to the Protestant Frederick V of the Palatinate, who accepted, but most German princes refused to support him, and by early 1620 the Bohemian Revolt had been suppressed.

When Frederick refused to admit defeat, the war expanded into the Palatinate, whose strategic importance drew in external powers, notably the Dutch Republic and Spain. By 1623, Spanish-Imperial forces had defeated Frederick, who was stripped of his possessions and exiled. Combined with Ferdinand’s support for the Catholic Counter-Reformation, this appeared to threaten other Protestant rulers within the Empire. They included Christian IV of Denmark, who was also Duke of Holstein; in 1625 he intervened in Northern Germany until forced to withdraw in 1629.

Confident of victory, Ferdinand now passed the Edict of Restitution, which sought to reverse Catholic property losses confirmed by Augsburg. This effectively destabilised large areas of North and Central Germany and provided an opportunity for Gustavus Adolphus of Sweden, who invaded the Empire in 1630. Backed by French subsidies, the Swedes and their German allies won a series of victories over Imperial forces, although Gustavus was killed in 1632. At Prague in 1635, Ferdinand made peace with his German opponents by accepting their autonomy. In return, they dissolved the Heilbronn and Catholic Leagues.

The defection of their German allies led France to join the war directly, which now became part of a wider European conflict. Fighting in Germany ended with the 1648 Peace of Westphalia, whose main provisions included Spanish confirmation of Dutch independence and acceptance of “German liberties” by the Austrian Habsburgs. By weakening the Habsburgs while increasing the status of France and Sweden, it led to a new balance of power on the continent.


The 1552 Peace of Passau ended a religious civil war between Protestants and Catholics in the Holy Roman Empire, while the 1555 Peace of Augsburg tried to prevent future conflict by fixing existing boundaries. Under the principle of cuius regio, eius religio, each of the 224 states was either Lutheran, then the most usual form of Protestantism, or Catholic, based on the religion of their ruler. Other provisions guaranteed the rights of substantial religious minorities in cities like Donauwörth, while Lutherans retained property taken from Catholics since 1552. However, various factors undermined the agreement.

In practice, Protestantism could not be contained within the 1555 boundaries; since Protestant rulers acquired lands and revenues from the Catholic church, this meant constant disputes over property. Additional complexity arose from the rapid growth of Calvinism post 1560, a Reformed faith not recognised by Augsburg and regarded by Lutherans with as much hostility as Catholics. Finally, economic and political objectives often took precedence over religion. Lutheran Saxony, Denmark-Norway and Sweden competed with Calvinist Brandenburg for control of the Baltic trade. To weaken their Habsburg opponents, Catholic France supported Protestants in the Dutch Republic and Electoral Palatinate, as well as Muslims in the Ottoman Empire.

Managing these issues was complicated since the Empire comprised nearly 1,800 separate entities in Germany, the Low Countries, Northern Italy, and areas like Alsace, now part of modern France. They ranged in size and importance from the seven Prince-electors who voted for the Holy Roman Emperor, down to Prince-bishoprics and City-states, such as Hamburg. Each member was represented in the Imperial Diet; prior to 1663, this assembled on an irregular basis, and was primarily a forum for discussion, rather than legislation.

While Emperors were elected, since 1440 this had been a Habsburg, the largest single landowner within the Empire; their lands included the Archduchy of Austria, the Kingdom of Bohemia, and the Kingdom of Hungary, with over eight million subjects. In 1556, Habsburg Spain became a separate entity, while retaining Imperial states such as the Duchy of Milan, and interests in Bohemia and Hungary; the two often co-operated, but their objectives did not always align. Then the predominant global power, the Spanish Empire included the Spanish Netherlands, much of Italy, the Philippines, and most of the Americas, while Austria remained focused on Central Europe.

Before Augsburg, unity of religion compensated for lack of strong central authority; once removed, it presented opportunities for those who sought to further weaken it. This included ambitious Imperial states like Lutheran Saxony and Catholic Bavaria, as well as France, which faced Habsburg territories on its borders in Flanders, Franche-Comté, and the Pyrenees. Disputes within the Empire drew in outside powers, many of whom held Imperial territories, including the Dutch Prince of Orange, hereditary ruler of Nassau-Dillenburg. Christian IV of Denmark was also Duke of Holstein, and it was in this capacity he joined the war in 1625.


These tensions occasionally resulted in full-scale conflict like the 1583 to 1588 Cologne War, caused by the conversion to Calvinism of its ruler. More common were disputes such as the 1606 ‘Battle of the Flags’ in Donauwörth, when riots broke out after the Lutheran majority blocked a Catholic religious procession. Emperor Rudolf approved intervention by the Catholic Maximilian of Bavaria, who was allowed to annex the town, changing it from Lutheran to Catholic under the principle of cuius regio, eius religio.

When the Imperial Diet opened in February 1608, both Lutherans and Calvinists united to demand formal re-confirmation of the Augsburg settlement. However, in return the Habsburg heir Archduke Ferdinand required the restoration of all property taken from the Catholic church since 1552, rather than the previous practice of courts ruling case by case. This threatened all Protestants, paralysed the Diet, and removed the perception of Imperial neutrality. Loss of faith in central authority meant towns and rulers began strengthening their fortifications and armies; outside travellers often commented on the growing militarisation of Germany in this period.

This increased when Frederick IV, Elector Palatine formed the Protestant Union and Maximilian responded by setting up the Catholic League in July 1609. While both Leagues were primarily designed to support the dynastic ambitions of their leaders, their creation combined with events like the 1609 to 1614 War of the Jülich Succession to increase tensions throughout the Empire. Some historians who see the war as primarily a European conflict argue Jülich marks its beginning, with Spain and Austria backing the Catholic candidate, France and the Dutch Republic the Protestant.

Outside powers became involved in an internal German dispute due to the imminent expiry of the 1609 Twelve Years’ Truce, which suspended the war between Spain and the Dutch. Before restarting hostilities, Ambrosio Spinola, commander in the Spanish Netherlands, had first to secure the Spanish Road, an overland route connecting Habsburg possessions in Italy to Flanders. This allowed Spinola to move troops and supplies by road, rather than sea where the Dutch navy held the advantage and by 1618, the only part not controlled by Spain ran through the Electoral Palatinate.

Since Emperor Matthias had no surviving children, in July 1617 Philip III of Spain agreed to support Ferdinand’s election as king of Bohemia and Hungary. In return, Ferdinand made concessions to Spain in Northern Italy and Alsace, and agreed to support their offensive against the Dutch. Delivering these commitments required his election as Emperor, which was not guaranteed; one alternative was Maximilian of Bavaria, who opposed the increase of Spanish influence in an area he considered his own, and tried to create a coalition with Saxony and the Palatinate to support his candidacy.

Another was Frederick V, Elector Palatine, who succeeded his father in 1610, and in 1613 married Elizabeth Stuart, daughter of James I of England. Four of the electors were Catholic, three Protestant; if this could be changed, it might result in a Protestant Emperor. When Ferdinand was elected king of Bohemia in 1617, he gained control of its electoral vote; however, his conservative Catholicism made him unpopular with the largely Protestant Bohemian nobility, who were also concerned at the erosion of their rights. In May 1618, these factors combined to bring about the Bohemian Revolt.

Phase I: 1618 to 1635

The Bohemian Revolt

The Jesuit educated Ferdinand once claimed he would rather see his lands destroyed than tolerate heresy for a single day. Appointed to rule the Duchy of Styria in 1595, within eighteen months he eliminated Protestantism in what was previously a stronghold of the Reformation. Focused on retaking the Netherlands, the Spanish Habsburgs preferred to avoid antagonising Protestants elsewhere, and recognised the dangers associated with Ferdinand’s fervent Catholicism, but accepted the lack of alternatives.

Ferdinand reconfirmed Protestant religious freedoms when elected king of Bohemia in May 1617, but his record in Styria led to the suspicion he was only awaiting a chance to overturn them. These concerns were exacerbated when a series of legal disputes over property were all decided in favour of the Catholic Church. In May 1618, Protestant nobles led by Count Thurn met in Prague Castle with Ferdinand’s two Catholic representatives, Vilem Slavata and Jaroslav Borzita. In an event known as the Second Defenestration of Prague, the two men and their secretary Philip Fabricius were thrown out of the castle windows, although all three survived.

Thurn established a new government, and the conflict expanded into Silesia and the Habsburg heartlands of Lower and Upper Austria, where much of the nobility was also Protestant. One of the most prosperous areas of the Empire, Bohemia’s electoral vote was also essential to ensuring Ferdinand succeeded Matthias as Emperor, and Habsburg prestige required its recapture. Chronic financial weakness meant prior to 1619 the Austrian Habsburgs had no standing army of any size, leaving them dependent on Maximilian and their Spanish relatives for money and men.

Spanish involvement inevitably drew in the Dutch, and potentially France, although the strongly Catholic Louis XIII faced his own Protestant rebels at home and refused to support them elsewhere. It also provided opportunities for external opponents of the Habsburgs, including the Ottoman Empire and Savoy. Funded by Frederick and the Duke of Savoy, a mercenary army under Ernst von Mansfeld succeeded in stabilising the Bohemian position over the winter of 1618. Attempts by Maximilian of Bavaria and John George of Saxony to broker a negotiated solution ended when Matthias died in March 1619, since it convinced many the Habsburgs were fatally damaged.

By mid-June, the Bohemian army under Thurn was outside Vienna; Mansfeld’s defeat by Spanish-Imperial forces at Sablat forced him to return to Prague, but Ferdinand’s position continued to worsen. Gabriel Bethlen, Calvinist Prince of Transylvania, invaded Hungary with Ottoman support, although the Habsburgs persuaded them to avoid direct involvement, helped by the outbreak of hostilities with Poland in 1620, followed by the 1623 to 1639 war with Persia.

On 19 August, the Bohemian Estates rescinded Ferdinand’s 1617 election as king, and on 26th, formally offered the crown to Frederick instead; two days later, Ferdinand was elected Emperor, making war inevitable if Frederick accepted. With the exception of Christian of Anhalt, his advisors urged him to reject it, as did the Dutch, the Duke of Savoy, and his father-in-law James. 17th century Europe was a highly structured and socially conservative society, and their lack of enthusiasm was due to the implications of removing a legally elected ruler, regardless of religion.

As a result, although Frederick accepted the crown and entered Prague in October 1619, his support gradually eroded over the next few months. In July 1620, the Protestant Union proclaimed its neutrality, while John George of Saxony agreed to back Ferdinand in return for Lusatia, and a promise to safeguard the rights of Lutherans in Bohemia. A combined Imperial-Catholic League army funded by Maximilian and led by Count Tilly pacified Upper and Lower Austria before invading Bohemia, where they defeated Christian of Anhalt at the White Mountain in November 1620. Although the battle was far from decisive, the rebels were demoralised by lack of pay, shortages of supplies, and disease, while the countryside had been devastated by Imperial troops. Frederick fled Bohemia and the revolt collapsed.

The Palatinate Campaign

By abandoning Frederick, the German princes hoped to restrict the dispute to Bohemia, but Maximilian’s dynastic ambitions made this impossible. In the October 1619 Treaty of Munich, Ferdinand agreed to transfer the Palatinate’s electoral vote to Bavaria and allow him to annex the Upper Palatinate. Many Protestants supported Ferdinand because they objected to deposing the legally elected king of Bohemia, and now opposed Frederick’s removal on the same grounds. Doing so turned the conflict into a contest between Imperial authority and “German liberties”, while Catholics saw an opportunity to regain lands lost since 1555. The combination destabilised large parts of the Empire.

The strategic importance of the Palatinate and its proximity to the Spanish Road drew in external powers; in August 1620, the Spanish occupied the Lower Palatinate. James responded to this attack on his son-in-law by sending naval forces to threaten Spanish possessions in the Americas and the Mediterranean, and announced he would declare war if Spinola had not withdrawn his troops by spring 1621. These actions were greeted with approval by his domestic critics, who considered his pro-Spanish policy a betrayal of the Protestant cause.

Spanish chief minister Olivares correctly interpreted this as an invitation to open negotiations, and in return for an Anglo-Spanish alliance offered to restore Frederick to his Rhineland possessions. Since Frederick demanded full restitution of his lands and titles, which was incompatible with the Treaty of Munich, hopes of reaching a negotiated peace quickly evaporated. When the Eighty Years War restarted in April 1621, the Dutch provided Frederick military support to regain his lands, along with a mercenary army under Mansfeld paid for with English subsidies. Over the next eighteen months, Spanish and Catholic League forces won a series of victories; by November 1622, they controlled most of the Palatinate, apart from Frankenthal, held by a small English garrison under Sir Horace Vere. Frederick and the remnants of Mansfeld’s army took refuge in the Dutch Republic.

At a meeting of the Imperial Diet in February 1623, Ferdinand forced through provisions transferring Frederick’s titles, lands, and electoral vote to Maximilian. He did so with support from the Catholic League, despite strong opposition from Protestant members, as well as the Spanish. The Palatinate was clearly lost; in March, James instructed Vere to surrender Frankenthal, while Tilly’s victory over Christian of Brunswick at Stadtlohn in August completed military operations. However, Spanish and Dutch involvement in the campaign was a significant step in internationalising the war, while Frederick’s removal meant other Protestant princes began discussing armed resistance to preserve their own rights and territories.

Danish Intervention (1625-1629)

With Saxony dominating the Upper Saxon Circle and Brandenburg the Lower, both kreis had remained neutral during the campaigns in Bohemia and the Palatinate. After Frederick was deposed in 1623, John George of Saxony and the Calvinist George William of Brandenburg feared Ferdinand intended to reclaim former Catholic bishoprics currently held by Lutherans. This seemed confirmed when Tilly’s Catholic League army occupied Halberstadt in early 1625.

As Duke of Holstein, Christian IV was also a member of the Lower Saxon circle, while Denmark’s economy relied on the Baltic trade and tolls from traffic through the Øresund. In 1621, Hamburg accepted Danish ‘supervision’, while his son Frederick became joint-administrator of Lübeck, Bremen, and Verden; possession ensured Danish control of the Elbe and Weser rivers.

Ferdinand had paid Wallenstein for his support against Frederick with estates confiscated from the Bohemian rebels, and now contracted with him to conquer the north on a similar basis. In May 1625, the Lower Saxony kreis elected Christian their military commander, although not without resistance; Saxony and Brandenburg viewed Denmark and Sweden as competitors, and wanted to avoid either becoming involved in the Empire. Attempts to negotiate a peaceful solution failed as the conflict in Germany became part of the wider struggle between France and their Habsburg rivals in Spain and Austria.

In the June 1624 Treaty of Compiègne, France subsidised the Dutch war against Spain for a minimum of three years, while in December 1625 the Dutch and English agreed to finance Danish intervention in the Empire. Hoping to create a wider coalition against Ferdinand, the Dutch invited France, Sweden, Savoy, and the Republic of Venice to join, but it was overtaken by events. In early 1626, Cardinal Richelieu, main architect of the alliance, faced a new Huguenot rebellion at home and in the March Treaty of Monzón, France withdrew from Northern Italy, re-opening the Spanish Road.

The Danish campaign plan involved three armies; the main force under Christian IV was to advance down the Weser, while Mansfeld attacked Wallenstein in Magdeburg and Christian of Brunswick linked up with the Calvinist Maurice of Hesse-Kassel. The advance quickly fell apart; Mansfeld was defeated at Dessau Bridge in April, and when Maurice refused to support him, Christian of Brunswick fell back on Wolfenbüttel, where he died of disease shortly after. The Danes were comprehensively beaten at Lutter in August, and Mansfeld’s army dissolved following his death in November.

Many of Christian’s German allies, such as Hesse-Kassel and Saxony, had little interest in replacing Imperial domination for Danish, while few of the subsidies agreed in the Treaty of the Hague were ever paid. Charles I of England allowed Christian to recruit up to 9,000 Scottish mercenaries, but they took time to arrive, and while able to slow Wallenstein’s advance, were insufficient to stop him. By the end of 1627, Wallenstein occupied Mecklenburg, Pomerania, and Jutland, and began making plans to construct a fleet capable of challenging Danish control of the Baltic. He was supported by Spain, for whom it provided an opportunity to open another front against the Dutch.

In May 1628, his deputy von Arnim besieged Stralsund, the only port with large enough shipbuilding facilities, but this brought Sweden into the war. Gustavus Adolphus despatched several thousand Scots and Swedish troops under Alexander Leslie to Stralsund, who was appointed governor.[58] Von Arnim was forced to lift the siege on 04 August, but three weeks later, Christian suffered another defeat at Wolgast. He began negotiations with Wallenstein, who despite his recent victories was concerned by the prospect of Swedish intervention, and thus anxious to make peace.

With Austrian resources stretched by the outbreak of the War of the Mantuan Succession, Wallenstein persuaded Ferdinand to agree relatively lenient terms in the June 1629 Treaty of Lübeck. Christian retained his German possessions of Schleswig and Holstein, in return for relinquishing Bremen and Verden, and abandoning support for the German Protestants. While Denmark kept Schleswig and Holstein until 1864, this effectively ended its reign as the predominant Nordic state.

Once again, the methods used to obtain victory explain why the war failed to end. Ferdinand paid Wallenstein by letting him confiscate estates, extort ransoms from towns, and allowing his men to plunder the lands they passed through, regardless of whether they belonged to allies or opponents. Anger at such tactics and his growing power came to a head in early 1628 when Ferdinand deposed the hereditary Duke of Mecklenburg, and appointed Wallenstein in his place. Although opposition to this act united all German princes regardless of religion, Maximilian of Bavaria was compromised by his acquisition of the Palatinate; while Protestants wanted Frederick restored and the position returned to that of 1618, the Catholic League argued only for pre-1627.

Made overconfident by success, in March 1629 Ferdinand passed an Edict of Restitution, which required all lands taken from the Catholic church after 1555 to be returned. While technically legal, politically it was extremely unwise, since doing so would alter nearly every single state boundary in North and Central Germany, deny the existence of Calvinism and restore Catholicism in areas where it had not been a significant presence for nearly a century. Well aware none of the princes involved would agree, Ferdinand used the device of an Imperial edict, once again asserting his right to alter laws without consultation. This new assault on ‘German liberties’ ensured continuing opposition and undermined his previous success.

Swedish Intervention (1630 to 1635)

Richelieu’s policy was to ‘arrest the course of Spanish progress’, and ‘protect her neighbours from Spanish oppression’. With French resources tied up in Italy, he helped negotiate the September 1629 Truce of Altmark between Sweden and Poland, freeing Gustavus Adolphus to enter the war. Partly a genuine desire to support his Protestant co-religionists, like Christian he also wanted to maximise his share of the Baltic trade that provided much of Sweden’s income.

Using Stralsund as a bridgehead, in June 1630 nearly 18,000 Swedish troops landed in the Duchy of Pomerania. Gustavus signed an alliance with Bogislaw XIV, Duke of Pomerania, securing his interests in Pomerania against the Catholic Polish-Lithuanian Commonwealth, another Baltic competitor linked to Ferdinand by family and religion. The 1632 to 1634 Smolensk War is considered a separate but related part of the Thirty Years’ War.

Expectations of widespread support proved unrealistic; by the end of 1630, the only new Swedish ally was Magdeburg, which was besieged by Tilly. Despite the devastation inflicted on their territories by Imperial soldiers, both Saxony and Brandenburg had their own ambitions in Pomerania, which clashed with those of Gustavus; previous experience also showed inviting external powers into the Empire was easier than getting them to leave.

However, once again Richelieu provided the requisite support; in the 1631 Treaty of Bärwalde, he provided funds for the Heilbronn League, a Swedish-led coalition of German Protestant states, including Saxony and Brandenburg.[69] Payments amounted to 400,000 Reichstaler, or one million livres, per year, plus an additional 120,000 Reichstalers for 1630. Though less than 2% of the total French state budget, it constituted over 25% of the Swedish budget and allowed Gustavus to support an army of 36,000. He won major victories at Breitenfeld in September 1631, then Rain in April 1632, where Tilly was killed.

After Tilly’s death, Ferdinand turned once again to Wallenstein; knowing Gustavus was overextended, he marched into Franconia and established himself at Fürth, threatening the Swedish supply chain. In late August, Gustavus incurred heavy losses in an unsuccessful assault on the town, arguably the greatest blunder in his German campaign. Two months later, the Swedes won a resounding victory at Lützen, where Gustavus was killed. Rumours now began circulating Wallenstein was preparing to switch sides, and in February 1634, Ferdinand issued orders for his arrest; on 25th, he was assassinated by one of his officers in Cheb.

Phase II: 1635 to 1648 (France Joins the War)

A serious Swedish defeat at Nördlingen in September 1634 threatened their participation, leading France to intervene directly. Under the April 1635 Treaty of Compiègne negotiated with Axel Oxenstierna, Richelieu agreed new subsidies for the Swedes. He also hired mercenaries led by Bernhard of Saxe-Weimar for an offensive in the Rhineland and declared war on Spain in May, beginning the 1635 to 1659 Franco-Spanish War. A few days later, Ferdinand agreed the Peace of Prague with the German states; he withdrew the Edict while the Heilbronn and Catholic Leagues were replaced by a single Imperial army, although Saxony and Bavaria retained control of their own forces. This is generally seen as the point when the conflict ceased to be primarily a German civil war.

After invading the Spanish Netherlands in May 1635, the poorly equipped French army collapsed, suffering 17,000 casualties from disease and desertion. A Spanish offensive in 1636 reached Corbie in Northern France; although it caused panic in Paris, lack of supplies forced them to retreat, and it was not repeated. In the March 1636 Treaty of Wismar, France formally joined the Thirty Years War in alliance with Sweden; a Swedish army under Johan Banér entered Brandenburg and re-established their position in North-East Germany at Wittstock on 04 October 1636.

Ferdinand II died in February 1637 and was succeeded by his son Ferdinand III, who faced a deteriorating military position. In March 1638, Bernhard destroyed an Imperial army at Rheinfelden, while his capture of Breisach in December secured French control of Alsace and severed the Spanish Road. In October, von Hatzfeldt defeated a Swedish-English-Palatine force at Vlotho but the main Imperial army under Matthias Gallas abandoned North-East Germany to the Swedes, unable to sustain itself in the devastated area. Banér defeated the Saxons at Chemnitz in April 1639, then entered Bohemia in May. Ferdinand was forced to divert Piccolomini’s army from Thionville, effectively ending direct military cooperation with Spain.

Pressure grew on Spanish minister Olivares to make peace, especially after attempts to hire Polish auxiliaries proved unsuccessful. Cutting the Spanish Road had forced Madrid to resupply their armies in Flanders by sea and in October 1639 a large Spanish convoy was destroyed at the Battle of the Downs. Dutch attacks on their possessions in Africa and the Americas caused unrest in Portugal, then part of the Spanish Empire and combined with heavy taxes caused revolts in both Portugal and Catalonia. After the French captured Arras in August 1640 and overran Artois, Olivares argued it was time to accept Dutch independence and prevent further losses in Flanders. The Empire remained a formidable power but could no longer subsidise Ferdinand, impacting his ability to continue the war.

Despite the death of Bernhard, over the next two years the Franco-Swedish alliance won a series of battles in Germany, including Wolfenbüttel in June 1641 and Kempen in January 1642. At Second Breitenfeld in October 1642, Lennart Torstenson inflicted almost 10,000 casualties on an Imperial army led by Archduke Leopold Wilhelm of Austria.[85] The Swedes captured Leipzig in December, giving them a significant new base in Germany, and although they failed to take Freiberg in February 1643, the Saxon army was reduced to a few garrisons.

While he accepted military victory was no longer possible, Ferdinand hoped to restrict peace negotiations to members of the Empire, excluding France and Sweden. Richelieu died in December 1642, followed by Louis XIII on 14 May 1643, leaving the five-year-old Louis XIV as king. His successor Cardinal Mazarin continued the same general policy, while French gains in Alsace allowed him to re-focus on the war against Spain in the Netherlands. On 19 May, Condé won a famous victory over the Spanish at Rocroi, although it was less decisive than often assumed.

By now, the devastation inflicted by 25 years of warfare meant all armies spent more time foraging than fighting. This forced them to become smaller and more mobile, with a greater emphasis on cavalry, shortened the campaigning seasons and restricted them to main supply lines. The French also had to rebuild their army in Germany after it was shattered by an Imperial-Bavarian force led by Franz von Mercy at Tuttlingen in November.

Three weeks after Rocroi, Ferdinand invited Sweden and France to attend peace negotiations in the Westphalian towns of Münster and Osnabrück, but talks were delayed when Christian of Denmark blockaded Hamburg and increased toll payments in the Baltic. This severely impacted the Dutch and Swedish economies and in December 1643 the Swedes began the Torstenson War by invading Jutland, with the Dutch providing naval support. Ferdinand pulled together an Imperial army under Gallas to attack the Swedes from the rear, which proved a disastrous decision. Leaving Wrangel to finish the war in Denmark, in May 1644 Torstenson marched into the Empire; Gallas was unable to stop him, while the Danes sued for peace after their defeat at Fehmarn in October 1644.

Ferdinand restarted peace talks in November, but his position worsened when Gallas’ army disintegrated; the remnants retreated into Bohemia, where they were scattered by Torstenson at Jankau in March 1645. In May, a Bavarian force under von Mercy destroyed a French detachment at Herbsthausen, before he was defeated and killed at Second Nördlingen in August. With Ferdinand unable to help, John George of Saxony signed a six-month truce with Sweden in September, followed by the March 1646 Treaty of Eulenberg in which he agreed to remain neutral until the end of the war.

This allowed the Swedes, now led by Wrangel, to put pressure on the peace talks by devastating first Westphalia, then Bavaria; by the autumn of 1646, Maximilian was desperate to end the war he was largely responsible for starting. At this point, Olivares publicised secret discussions initiated by Mazarin in early 1646, in which he offered to exchange Catalonia for the Spanish Netherlands; angered by what they viewed as betrayal and concerned by French ambitions in Flanders, the Dutch agreed a truce with Spain in January 1647. Seeking to release French troops and prevent further Swedish gains by neutralising Bavaria, Mazarin negotiated the Truce of Ulm, signed on 14 March 1647 by Bavaria, Cologne, France, and Sweden.

Turenne, French commander in the Rhineland, was ordered to attack the Spanish Netherlands but the plan fell apart when his mostly German troops mutinied. Bavarian general Johann von Werth declared his loyalty to the Emperor and refused to comply with the truce, forcing Maximilian to do the same. In September, he ordered his army under Bronckhorst-Gronsfeld to link up with the Imperial commander von Holzappel. Outnumbered by a Franco-Swedish army under Wrangel and Turenne, they were defeated at Zusmarshausen in May 1648, while von Holzappel was killed. Montecuccoli extracted most of his troops but all the baggage and artillery was lost, ending any offensive capability.

While Turenne and Wrangel continued to devastate Bavaria, a second Swedish force attacked Prague, seizing the castle and Malá Strana district in July. The main objective was to gain as much loot as possible before the war ended; they failed to take the Old Town but captured the Imperial library, along with treasures including the Codex Gigas, now in Stockholm. On 05 November, news arrived that Ferdinand had signed peace treaties with France and Sweden on 24 October, ending the war.

The Conflict Outside Germany

Northern Italy

Northern Italy had been contested by France and the Habsburgs for centuries, since it was vital for control of South-West France, an area with a long history of opposition to the central authorities. While Spain remained the dominant power in Italy, its reliance on long exterior lines of communication was a potential weakness, especially the Spanish Road; this overland route allowed them to move recruits and supplies from Naples and Lombardy to their army in Flanders.

French policy was to seek to disrupt this road wherever possible, either by attacking the Spanish-held Duchy of Milan, or by blocking the Alpine passes. The strategic importance of the Duchy of Mantua meant when the direct male line became extinct in December 1627, both powers became involved in the 1628 to 1631 War of the Mantuan Succession. The situation was complicated by Savoy, which saw an opportunity to gain territory; in March 1629, the French stormed Savoyard positions in the Pas de Suse, lifted the siege of Casale and captured the strategic fortress of Pinerolo.

France and Savoy made peace in the April 1629 Treaty of Suza, which allowed French troops passage through Savoy, and recognised their control of Casale and Pinerolo. Possession of these fortresses gave France effective control of Piedmont, protected the Alpine passes into Southern France, and allowed them to threaten Milan at will.

Between 1629 and 1631, plague exacerbated by troop movements killed 60,000 in Milan and 46,000 in Venice, with proportionate losses elsewhere. Combined with the diversion of Imperial resources caused by Swedish intervention in 1630, this led to the Treaty of Cherasco in June 1631. The French candidate, Charles I Gonzaga, was confirmed as Duke of Mantua; although Richelieu’s representative, Cardinal Mazarin, agreed to evacuate Pinerolo, it was later secretly returned under an agreement with Victor Amadeus I, Duke of Savoy. With the exception of the 1639 to 1642 Piedmontese Civil War, this secured the French position in Northern Italy for the next twenty years.

Catalonia: Reapers’ War

Throughout the 1630s, attempts to increase taxes to pay for the costs of the war in the Netherlands led to protests throughout Spanish territories; in 1640, these erupted into open revolts in Portugal and Catalonia, supported by Richelieu as part of his ‘war by diversion’. Prompted by France, the rebels proclaimed the Catalan Republic in January 1641. The Madrid government quickly assembled an army of 26,000 men to crush the revolt, and on 23 January, they defeated the Catalans at Martorell. The French now persuaded the Catalan Courts to recognise Louis XIII as Count of Barcelona, and ruler of the Principality of Catalonia.

Three days later, a combined French-Catalan force defeated the Spanish at Montjuïc, a victory which secured Barcelona. However, the rebels soon found the new French administration differed little from the old, turning the war into a three-sided contest between the Franco-Catalan elite, the rural peasantry, and the Spanish. There was little serious fighting after France took control of Perpignan and Roussillon, establishing the modern Franco-Spanish border in the Pyrenees. In 1651, Spain recaptured Barcelona, ending the revolt.

Outside Europe

In 1580, Philip II of Spain became ruler of the Portuguese Empire; long-standing commercial rivals, the 1602 to 1663 Dutch-Portuguese War was an offshoot of the Dutch fight for independence from Spain. The Portuguese dominated the trans-Atlantic economy known as the Triangular trade, in which slaves were transported from West Africa and Portuguese Angola to work on plantations in Portuguese Brazil, which exported sugar and tobacco to Europe. Known by Dutch historians as the ‘Great Design”, control of this trade would not only be extremely profitable but also deprive the Spanish of funds needed to finance their war in the Netherlands.

The Dutch West India Company was formed in 1621 to achieve this purpose and a Dutch fleet captured the Brazilian port of Salvador, Bahia in 1624. After it was retaken by the Portuguese in 1625, a second fleet established Dutch Brazil in 1630, which was returned until 1654. The second part was seizing slave trading hubs in Africa, chiefly Angola and São Tomé; supported by the Kingdom of Kongo, whose position was threatened by Portuguese expansion, the Dutch successfully occupied both in 1641.

Spain’s inability or unwillingness to provide protection against these attacks increased Portuguese resentment and were major factors in the outbreak of the Portuguese Restoration War in 1640. Although ultimately expelled from Brazil, Angola and São Tomé, the Dutch retained the Cape of Good Hope, as well as Portuguese trading posts in Malacca, the Malabar Coast, the Moluccas and Ceylon.

Peace of Westphalia (1648)

Preliminary discussions began in 1642 but only became serious in 1646; a total of 109 delegations attended at one time or other, with talks split between Münster and Osnabrück. The Swedes rejected a proposal that Christian of Denmark act as mediator, with Papal Legate Fabio Chigi and the Venetian Republic appointed instead. The Peace of Westphalia consisted of three separate agreements; the Peace of Münster between Spain and the Dutch Republic, the treaty of Osnabrück between the Empire and Sweden, plus the treaty of Münster between the Empire and France.

The Peace of Münster was the first to be signed on 30 January 1648; it was part of the Westphalia settlement because the Dutch Republic was still technically part of the Spanish Netherlands and thus Imperial territory. The treaty confirmed Dutch independence, although the Imperial Diet did not formally accept that it was no longer part of the Empire until 1728. The Dutch were also given a monopoly over trade conducted through the Scheldt estuary, confirming the commercial ascendancy of Amsterdam; Antwerp, capital of the Spanish Netherlands and previously the most important port in Northern Europe, would not recover until the late 19th century.

Negotiations with France and Sweden were conducted in conjunction with the Imperial Diet, and were multi-sided discussions involving many of the German states. This resulted in the treaties of Münster and Osnabrück, making peace with France and Sweden respectively. Ferdinand resisted signing until the last possible moment, doing so on 24 October only after a crushing French victory over Spain at Lens, and with Swedish troops on the verge of taking Prague.

Taken as a whole, the consequences of these two treaties can be divided into the internal political settlement and external territorial changes. Ferdinand accepted the supremacy of the Imperial Diet and legal institutions, reconfirmed the Augsburg settlement, and recognised Calvinism as a third religion. In addition, Christians residing in states where they were a minority, such as Catholics living under a Lutheran ruler, were guaranteed freedom of worship and equality before the law. Brandenburg-Prussia received Farther Pomerania, and the bishoprics of Magdeburg, Halberstadt, Kammin, and Minden. Frederick’s son Charles Louis regained the Lower Palatinate and became the eighth Imperial elector, although Bavaria kept the Upper Palatinate and its electoral vote.

Externally, the treaties formally acknowledged the independence of the Dutch Republic and the Swiss Confederacy, effectively autonomous since 1499. In Lorraine, the Three Bishoprics of Metz, Toul and Verdun, occupied by France since 1552, were formally ceded, as were the cities of the Décapole in Alsace, with the exception of Strasbourg and Mulhouse. Sweden received an indemnity of five million thalers, the Imperial territories of Swedish Pomerania, and Prince-bishoprics of Bremen and Verden; this gave them a seat in the Imperial Diet.

The Peace was later denounced by Pope Innocent X, who regarded the bishoprics ceded to France and Brandenburg as property of the Catholic church, and thus his to assign. It also disappointed many exiles by accepting Catholicism as the dominant religion in Bohemia, Upper and Lower Austria, all of which were Protestant strongholds prior to 1618. Fighting did not end immediately, since demobilising over 200,000 soldiers was a complex business, and the last Swedish garrison did not leave Germany until 1654.

The settlement failed to achieve its stated intention of achieving a ‘universal peace’. Mazarin insisted on excluding the Burgundian Circle from the treaty of Münster, allowing France to continue its campaign against Spain in the Low Countries, a war that continued until the 1659 Treaty of the Pyrenees. The political disintegration of the Polish commonwealth led to the 1655 to 1660 Second Northern War with Sweden, which also involved Denmark, Russia and Brandenburg, while two Swedish attempts to impose its control on the port of Bremen failed in 1654 and 1666.

It has been argued the Peace established the principle known as Westphalian sovereignty, the idea of non-interference in domestic affairs by outside powers, although this has since been challenged. The process, or ‘Congress’ model, was adopted for negotiations at Aix-la-Chapelle in 1668, Nijmegen in 1678, and Ryswick in 1697; unlike the 19th century ‘Congress’ system, these were to end wars, rather than prevent them, so references to the ‘balance of power’ can be misleading.

Human and Financial Cost of the War

Historians often refer to the ‘General Crisis’ of the mid-17th century, a period of sustained conflict in states such as China, the British Isles, Tsarist Russia and the Holy Roman Empire. In all these areas, war, famine and disease inflicted severe losses on local populations. While the Thirty Years War ranks as one of the worst of these events, precise numbers are disputed; 19th century nationalists often increased them to illustrate the dangers of a divided Germany.

By modern standards, the number of soldiers involved was relatively low; most battles were fought by opposing forces of around 13,000 to 20,000, the largest being Alte Veste in 1632, which featured a combined total of 70,000-85,000. However, the conflict has been described as one of the greatest medical catastrophes in history. Well into the 19th century, far more soldiers died of disease than in battle; of an estimated 700,000 to 1,200,000 military casualties between 1618 and 1648, only 25 to 30% were the result of combat, or combat-related injuries.

Based on local records, military action accounted for less than 3% of civilian deaths; the major causes were starvation (12%), bubonic plague (64%), typhus (4%), and dysentery (5%). Although regular outbreaks of disease were common for decades prior to 1618, the conflict greatly accelerated their spread. This was due to the influx of soldiers from foreign countries, the shifting locations of battle fronts, as well as the displacement of rural populations into already crowded cities. Poor harvests throughout the 1630s and repeated plundering of the same areas led to widespread famine; contemporaries record people eating grass, or too weak to accept alms, while instances of cannibalism were common.

The modern consensus is the population of the Holy Roman Empire declined from 18-20 million in 1600 to 11-13 million in 1650, and did not regain pre-war levels until 1750. Nearly 50% of these losses appear to have been incurred during the first period of Swedish intervention from 1630 to 1635. The high mortality rate compared to the Wars of the Three Kingdoms in Britain may partly be due to the reliance of all sides on foreign mercenaries, often unpaid and required to live off the land. Lack of a sense of ‘shared community’ resulted in atrocities such as the destruction of Magdeburg, in turn creating large numbers of refugees who were extremely susceptible to sickness and hunger. While flight saved lives in the short-term, in the long run it often proved catastrophic.

In 1940, agrarian historian Günther Franz published Der Dreissigjährige Krieg und das Deutsche Volk, a detailed analysis of regional data from across Germany; membership of the Nazi Party meant his objectivity was challenged post-1945, but recent reviews support his general findings. He concluded “about 40% of the rural population fell victim to the war and epidemics; in the cities,…33%”. There were wide regional variations; in the Duchy of Württemberg, the number of inhabitants fell by nearly 60%. These figures can be misleading, since Franz calculated the absolute decline in pre and post-war populations, or ‘total demographic loss’. They therefore include factors unrelated to death or disease, such as permanent migration to areas outside the Empire or lower birthrates, a common but less obvious impact of extended warfare.

Although some towns may have overstated their losses to avoid taxes, individual records confirm serious declines; from 1620 to 1650, the population of Munich fell from 22,000 to 17,000, that of Augsburg from 48,000 to 21,000. The financial impact is less clear; while the war caused short-term economic dislocation, overall it accelerated existing changes in trading patterns. It does not appear to have reversed ongoing macro-economic trends, such as the reduction of price differentials between regional markets, and a greater degree of market integration across Europe. The death toll may have improved living standards for the survivors; one study shows wages in Germany increased by 40% in real terms between 1603 and 1652.

Social Impact

The breakdown of social order caused by the war was often more significant and longer lasting than the immediate damage. The collapse of local government created landless peasants, who banded together to protect themselves from the soldiers of both sides, and led to widespread rebellions in Upper Austria, Bavaria and Brandenburg. Soldiers devastated one area before moving on, leaving large tracts of land empty of people and changing the eco-system. Food shortages were worsened by an explosion in the rodent population; Bavaria was overrun by wolves in the winter of 1638, its crops destroyed by packs of wild pigs the following spring.

Contemporaries spoke of a ‘frenzy of despair’ as people sought to make sense of the turmoil and hardship unleashed by the war. Their attribution by some to supernatural causes led to a series of Witch-hunts, beginning in Franconia in 1626 and quickly spreading to other parts of Germany, which were often exploited for political purposes. They originated in the Bishopric of Würzburg, an area with a history of such events going back to 1616 and now re-ignited by Bishop von Ehrenberg, a devout Catholic eager to assert the church’s authority in his territories. By the time he died in 1631, over 900 people from all levels of society had been executed.

At the same time, Prince-Bishop Johann von Dornheim held a similar series of large-scale witch trials in the nearby Bishopric of Bamberg. A specially designed Malefizhaus, or ‘crime house’, was erected containing a torture chamber, whose walls were adorned with Bible verses, where the accused were interrogated. These trials lasted five years and claimed over one thousand lives, including long-time Bürgermeister, or Mayor, Johannes Junius, and Dorothea Flock, second wife of Georg Heinrich Flock, whose first wife had also been executed for witchcraft in May 1628. During 1629, another 274 suspected witches were killed in the Bishopric of Eichstätt, plus another 50 in the adjacent Duchy of Palatinate-Neuburg.

Elsewhere, persecution followed Imperial military success, expanding into Baden and the Palatinate following their reconquest by Tilly, then into the Rhineland. Mainz and Trier also witnessed the mass killing of suspected witches, as did Cologne, where Ferdinand of Bavaria presided over a particularly infamous series of witchcraft trials, including that of Katharina Henot, who was executed in 1627. In 2012, she and other victims were officially exonerated by the Cologne City Council.

The extent to which these witch-hunts were symptomatic of the impact of the conflict on society is debatable, since many took place in areas relatively untouched by the war. Ferdinand and his advisors were concerned the brutality of the Würzburg and Bamberg trials would discredit the Counter-Reformation, and active persecution largely ended by 1630. A scathing condemnation of the trials, Cautio Criminalis, was written by professor and poet Friedrich Spee, himself a Jesuit and former “witch confessor”. This influential work was later credited with ending the practice in Germany, and eventually throughout Europe.

Political Consequences

The Peace reconfirmed “German liberties”, ending Habsburg attempts to convert the Holy Roman Empire into an absolutist state similar to Spain. This allowed Bavaria, Brandenburg-Prussia, Saxony and others to pursue their own policies, while Sweden gained a permanent foothold in the Empire. Despite these setbacks, the Habsburg lands suffered less from the war than many others and became a far more coherent bloc with the absorption of Bohemia, and restoration of Catholicism throughout their territories.

By laying the foundations of the modern nation state, Westphalia changed the relationship of subjects and their rulers. Previously, many had overlapping, sometimes conflicting political and religious allegiances; they were now understood to be subject first and foremost to the laws and edicts of their respective state authority, not to the claims of any other entity, be it religious or secular. This made it easier to levy national armies of significant size, loyal to their state and its leader; one lesson learned from Wallenstein and the Swedish invasion was the need for their own permanent armies, and Germany as a whole became a far more militarised society.

The benefits of Westphalia for the Swedes proved short-lived. Unlike French gains which were incorporated into France, Swedish territories remained part of the Empire, and they became members of the Lower and Upper Saxon kreis. While this gave them seats in the Imperial Diet, it also brought them conflict with both Brandenburg-Prussia and Saxony, who were competitors in Pomerania. The income from their imperial possessions remained in Germany and did not benefit the kingdom of Sweden; although they retained Swedish Pomerania until 1815, much of it was ceded to Prussia in 1679 and 1720.

Arguably, France gained more from the Thirty Years’ War than any other power; by 1648, most of Richelieu’s objectives had been achieved. They included separation of the Spanish and Austrian Habsburgs, expansion of the French frontier into the Empire, and an end to Spanish military supremacy in Northern Europe. Although the Franco-Spanish conflict continued until 1659 and Spain remained a global force for another two centuries, Westphalia allowed Louis XIV of France to complete the process of replacing her as the predominant European power.

While differences over religion remained an issue throughout the 17th century, it was the last major war in Continental Europe in which it can be said to be a primary driver; later conflicts were either internal, such as the Camisards revolt in South-Western France, or relatively minor like the 1712 Toggenburg War. It created the outlines of a Europe that persisted until 1815 and beyond; the nation-state of France, the beginnings of a unified Germany and separate Austro-Hungarian bloc, a diminished but still significant Spain, independent smaller states like Denmark, Sweden and Switzerland, along with a Low Countries split between the Dutch Republic and what became Belgium in 1830.


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