Thirty Years' War

Background: 1556 to 1618

Disputes occasionally resulted in full-scale conflict like the 1583 to 1588 Cologne War, triggered when its ruler converted to Calvinism. More common were events 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. In return, he was allowed to annex the town, and, as agreed at Augsburg, the official religion changed from Lutheran to Catholic.

When the Imperial Diet opened in February 1608, both Lutherans and Calvinists sought re-confirmation of the Augsburg settlement. In return, the Habsburg heir Archduke Ferdinand required the immediate restoration of any property taken from the Catholic Church since 1555, as opposed to the previous practice whereby each case was assessed separately. By threatening all Protestants, his demand 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, with foreign travellers often commenting on the militarisation of Germany in this period. When Frederick IV, Elector Palatine formed the Protestant Union in 1608, Maximilian responded by setting up the Catholic League in July 1609. Both were largely vehicles for their leaders' dynastic ambitions, but when combined with the 1609 to 1614 War of the Jülich Succession, the result was to increase tensions throughout the empire. Some historians who see the war as primarily a European conflict argue that Jülich marks its beginning, with Spain and Austria backing the Catholic candidate, France and the Dutch Republic the Protestant.

What began as an internal dynastic dispute within the empire drew in external powers due to the imminent expiry of the 1609 Twelve Years' Truce, which suspended the Eighty Years' War between Spain and the Dutch Republic. Before restarting hostilities, Ambrosio Spinola, commander in the Spanish Netherlands, needed to secure the Spanish Road, an overland route connecting Habsburg possessions in Italy to Flanders. This allowed him to move troops and supplies by road, rather than sea where the Dutch navy was dominant; 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 II'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. Doing so required his election as emperor, which was not guaranteed; Maximilian of Bavaria, who opposed the increase of Spanish influence in an area he considered his own, tried to create a coalition to support his candidacy.

Another option was Frederick V, Elector Palatine, a Calvinist who in 1613 married Elizabeth of Bohemia, daughter of James I of England. When Ferdinand was elected king of Bohemia in 1617, he also gained control of its electoral vote, but his conservative Catholicism made him unpopular with the mostly Protestant Bohemian nobility, who were also concerned about the erosion of their rights. Since the seven electors previously consisted of three Protestants and four Catholics, replacing Ferdinand with Frederick would alter the religious balance, making possible the election of a Protestant emperor and the end of Habsburg predominance. These factors combined to bring about the Bohemian Revolt in May 1618.

Phase I: 1618 to 1635

Bohemian Revolt

Ferdinand once claimed he would rather see his lands destroyed than tolerate heresy within them. Less than 18 months after taking control of Styria in 1595, he had eliminated Protestantism in what had been a stronghold of the Reformation. Their war in the Netherlands meant the Spanish Habsburgs preferred to avoid antagonising Protestants elsewhere. However, while recognising the dangers of Ferdinand's fervent Catholicism, they ultimately supported his claim due to lack of alternatives.

Elected king of Bohemia in May 1617, Ferdinand reconfirmed Protestant religious freedoms, but his record in Styria led to the suspicion he was only awaiting a chance to overturn them. These concerns were heightened after 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 what became known as the Third Defenestration of Prague, both men were thrown out of the castle windows along with their secretary Filip Fabricius, although all three survived.

Thurn established a Protestant-dominated government in Bohemia, while unrest expanded into Silesia and the Habsburg heartlands of Lower and Upper Austria, where much of the nobility was also Protestant. Losing control of these threatened the entire Habsburg state, while in addition to its crucial electoral vote, Bohemia was one of the most prosperous areas of the Empire. Regaining control was vital for the Austrian Habsburgs, but chronic financial weakness left them dependent on Maximilian and Spain for the resources needed to achieve this.

Spanish involvement in Bohemia drew in the Dutch and their ally, France, although the strongly Catholic Louis XIII faced his own domestic Protestant rebellion and refused to support them elsewhere. Elsewhere, Charles Emmanuel I, Duke of Savoy helped Frederick fund a mercenary army under Ernst von Mansfeld, which was sent to support the Bohemian rebels. Attempts by Maximilian and John George of Saxony to broker a negotiated solution ended when Emperor Matthias died in March 1619, since many believed the loss of his authority and influence had fatally damaged the Habsburgs.

By mid-June 1619, an army led by Thurn was outside Vienna, and despite defeating Mansfeld at Sablat, Ferdinand's position continued to worsen. Gabriel Bethlen, the Calvinist Prince of Transylvania, invaded Hungary and besieged Vienna with Ottoman support, although war with Poland–Lithuania in 1620, followed by the 1623 to 1639 conflict with Persia, prevented their direct participation.

On 19 August, the Bohemian Estates rescinded Ferdinand's 1617 election as king and a week later formally offered the crown to Frederick. On 28 August, Ferdinand was elected Holy Roman Emperor, making war inevitable if Frederick accepted the Bohemian crown. Most of Frederick's advisors urged him to reject it, as did the Duke of Savoy, and his father-in-law James I.

However, he received backing from Christian of Anhalt, along with Maurice of Orange, for whom conflict in Germany was a means to divert Spanish resources from the Netherlands. The Dutch offered subsidies to Frederick and the Protestant Union, helped raise loans for Bohemia, and provided weapons and munitions. However, wider European support failed to materialise, largely due to lack of enthusiasm for removing a legally elected ruler, regardless of religion.

Although Frederick accepted the crown and entered Prague in October 1619, his support eroded over the next few months. In July 1620, the Protestant Union proclaimed its neutrality, while John George of Saxony backed Ferdinand in return for the cession of Lusatia and a guarantee of Lutheran rights in Bohemia. Maximilian of Bavaria funded a combined Imperial-Catholic League army led by Count Tilly and the Count de Bucquoy, which pacified Upper and Lower Austria and occupied western Bohemia before marching on Prague. Defeated at the Battle of White Mountain in November 1620, the Bohemian army disintegrated, and Frederick fled the country.

Palatinate campaign

By abandoning Frederick, the German princes hoped to restrict the dispute to Bohemia, an objective thwarted by Maximilian's dynastic ambitions. In the October 1619 Treaty of Munich, Ferdinand transferred the Palatinate's electoral vote to Bavaria, and allowed Maximilian to annex the Upper Palatinate. Many Protestants had supported Ferdinand against Frederick because they opposed the deposition of a legally elected ruler, and now objected to his removal on the same grounds. For Catholics, it presented an opportunity to regain lands and properties lost since 1555, a combination which destabilised large parts of the Empire.

At the same time, Spain was drawn into the conflict due to the strategic importance of the Spanish Road, and its proximity to the Palatinate. When an army led by Córdoba occupied the Lower Palatinate in October 1619, James I sent English naval forces against Spanish colonies in the Americas, and threatened war if Spanish troops were not withdrawn by spring 1621. These actions were primarily designed to placate his opponents in Parliament, for whom his pro-Spanish policy was a betrayal of the Protestant cause. Spanish chief minister Count-Duke Olivares correctly interpreted them as an invitation to open negotiations, and in return for an Anglo-Spanish alliance offered to restore Frederick to his Rhineland possessions.

Since Frederick's demand for full restitution of his lands and titles was incompatible with the Treaty of Munich, hopes of a negotiated peace quickly evaporated. Despite defeat in Bohemia, Frederick still had allies including Georg Friedrich of Baden and Christian of Brunswick, while the Dutch provided military support and his father-in-law James funded an army of mercenaries under Mansfeld. However, failure to co-ordinate effectively led to defeats at Wimpfen in May 1622, after which Georg Friedrich made peace, and Höchst in June.

By November 1622, Spanish and imperial troops controlled most of the Palatinate, apart from Frankenthal, which was held by a small English garrison under Sir Horace Vere. After Höchst, Mansfeld and Christian united at Hagenau before moving towards the Netherlands. They were stopped by Córdoba at Fleurus, but the Protestant army escaped destruction, and made it to Bergen op Zoom. Frederick arrived in the Netherlands in 1622, where he lived in The Hague until his death in November 1632.

When the Imperial Diet met 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, and in March Vere surrendered Frankenthal, while campaigning ended with Tilly's victory over Christian of Brunswick at Stadtlohn in August. However, Spanish and Dutch involvement was a significant step in internationalising the war, while Frederick's removal meant other Protestant princes began planning how to preserve their own rights and territories.

Danish intervention (1625–1629)

With Saxony dominating the Upper Saxon Circle and Brandenburg the Lower, both kreise remained neutral in the early stages. However, Frederick's deposition in 1623 united the Lutheran John George of Saxony and Calvinist George William, Elector of Brandenburg, over concerns Ferdinand intended to reclaim Catholic territories. These were strengthened in early 1625 when territories held by Protestants since 1566 were returned by Tilly to the Roman Catholic Diocese of Halberstadt.

As Duke of Holstein, Christian IV was also a member of the Lower Saxon circle, while the Danish 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, thus ensuring Danish control of the Elbe and Weser rivers.

Ferdinand had paid Albrecht von 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 this was initially opposed by Saxony and Brandenburg, who 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 had agreed to subsidise the Dutch war against Spain for a minimum of three years, while in the December 1625 Treaty of The Hague, 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, Transylvania, 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 and the critical Valtellina Pass, re-opening the Spanish Road.

Dutch and English subsidies enabled Christian to devise an ambitious three-part campaign plan. While he led the main force down the Weser, Mansfeld would attack Wallenstein in Magdeburg, supported by forces led by Christian of Brunswick and Maurice of Hesse-Kassel. However, Mansfeld was defeated at Dessau Bridge in April, and when Maurice refused to support him, Christian of Brunswick fell back to Wolfenbüttel, where he died of disease shortly after. The Danes were comprehensively beaten at Lutter in August, and Mansfeld's army retreated south to the Ottoman Empire, where his army dissolved after his death in November.

Many of Christian's German allies, such as Hesse-Kassel, had little interest in replacing imperial domination with Danish, while few of the Dutch or English subsidies were ever paid. Charles I of England allowed Christian to recruit up to 9,000 Scottish mercenaries, but they took time to arrive, and although able to slow Wallenstein's advance, were insufficient to stop him. By the end of 1627, Wallenstein had 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.

On 13 May 1628, his deputy von Arnim besieged Stralsund, the only port with facilities large enough to build this fleet. Gustavus Adolphus responded by sending several thousand Scots to Stralsund under Alexander Leslie, who was also appointed governor. Von Arnim abandoned the siege on 4 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 Ferdinand's resources stretched by the outbreak of the War of the Mantuan Succession, Wallenstein persuaded him to agree relatively lenient terms in the June 1629 Treaty of Lübeck. These allowed Christian to retain 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 period as a major power in the Baltic region.

Once again, the methods used to obtain victory explain why the war failed to end. Ferdinand's chronic financial weakness meant Wallenstein raised money by demanding ransoms from towns, while his men plundered the local territory, regardless of whether it belonged to allies or opponents. When Ferdinand deposed the hereditary Duke of Mecklenburg in early 1628 and appointed Wallenstein in his place, the act united all German princes in opposition, regardless of religion. However, Maximilian's desire to retain the Palatinate meant the Catholic League argued only for a return to the position prevailing before 1627, while Protestants wanted that of 1618.

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.

At the same time, Madrid was reluctant to antagonise German Protestants with momentum in the Eighty Years' War moving in favour of the Dutch. The weakening of Spanish finances led to the loss of Oldenzaal in 1626, followed by Groenlo in 1627. This was made worse by the Dutch capture of the Spanish treasure fleet at Matanzas in 1628, while the Mantuan War diverted resources from the Netherlands, allowing Frederick Henry to besiege 's-Hertogenbosch in 1629. Imperial intervention could not prevent its fall, ending Spanish hopes of stopping trade with the Dutch East Indies.

Sweden invades Germany (1630–1635)

From 1626 to 1629, Gustavus was engaged in a war with Poland–Lithuania, ruled by his Catholic cousin Sigismund, who also claimed the Swedish throne and was backed by Ferdinand II. Once this conflict ended, and with only a few minor states like Hesse-Kassel still openly opposing Ferdinand, Gustavus became an obvious ally for Richelieu. In September 1629, the latter helped negotiate the Truce of Altmark between Sweden and Poland–Lithuania, freeing Gustavus 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.

After diplomatic negotiations with Ferdinand II failed, Gustavus landed in Pomerania in June 1630 with nearly 18,000 troops. Using Stralsund as a bridgehead, he marched south along the Oder towards Stettin. This allowed him to coerce Bogislaw XIV of Pomerania, into an alliance which secured Swedish interests in Pomerania against Poland–Lithuania, who instead initiated the 1632 to 1634 Smolensk War with Russia.

Although they had successfully secured their eastern flank, Swedish expectations of widespread German support proved unrealistic. By the end of 1630, their only new ally was the Administrator of Magdeburg, Christian William whose capital was under siege by Tilly. Despite the devastation inflicted by Wallenstein, Saxony and Brandenburg were ambivalent about Swedish intervention. Both states had their own ambitions in Pomerania, while experience showed inviting external powers into the Empire was easier than getting them to leave.

Gustavus put pressure on Brandenburg by sacking Küstrin and Frankfurt an der Oder and then bombarding George William in Berlin, while the Sack of Magdeburg in May 1631 provided a powerful warning of the consequences of imperial victory. Once again, French financial power bridged differences between the potential allies, and under the 1631 Treaty of Bärwalde, Richelieu agreed to fund the Swedes and German states including Hesse-Kassel, Saxony, and Brandenburg. Payments amounted to 400,000 Reichstaler per year, or one million livres, enabling Sweden to support a total of 36,000 troops.

With this army, Gustavus invaded southern Germany, winning victories at Breitenfeld in September 1631, then Rain in April 1632, where Tilly was killed. However, Wallenstein realised the Swedes were overextended, and established himself at Fürth, across their supply lines to the Baltic. At the Battle of the Alte Veste in late August, a failed Swedish assault on the Imperial camp outside the town was bloodily repulsed, arguably the greatest blunder committed by Gustavus during his German campaign.

Two months later, the Swedes and Imperialists met at Lützen, where both sides suffered heavy casualties. Gustavus himself was killed and some Swedish units incurred losses of over 60%. Fighting continued until dusk when Wallenstein retreated, abandoning his artillery and wounded. Despite the loss of Gustavus, most commentators consider the battle a Swedish victory, although the result continues to be disputed.

After his death, Gustavus' policies were continued by his Chancellor Axel Oxenstierna, and Bernard of Saxe-Weimar and Gustav Horn. With French backing, Sweden and a number of smaller German states formed the Heilbronn League in April 1633, although Brunswick-Lüneburg, Saxony, and Brandenburg remained outside. In July, the Swedes and their allies defeated a Bavarian army at Oldendorf. Wallenstein's critics claimed this was due to his failure to support them, while rumours spread that he was preparing to switch sides. Ferdinand II ordered his arrest in February 1634, and he was assassinated by his own officers in Cheb on 25th.

The loss of Wallenstein and his organisation left Ferdinand II reliant on Spain for military support. Since their main concern was to re-open the Spanish Road for their campaign against the Dutch, the focus of the war now shifted from the north to the Rhineland and Bavaria. Cardinal-Infante Ferdinand of Austria, new Governor of the Spanish Netherlands, raised an army of 18,000 in Italy, which met up with 15,000 Imperial troops at Donauwörth on 2 September 1634. Four days later, their combined army defeated Horn and Bernard at Nördlingen, a result that cost Sweden control of southern Germany.

Phase II: French intervention, 1635 to 1648

By triggering direct French intervention, Nördlingen expanded the conflict rather than ending it. Richelieu provided the Swedes with new subsidies, hired mercenaries led by Bernard of Saxe-Weimar for an offensive in the Rhineland, and in May 1635 initiated the Franco–Spanish War (1635–1659). A few days later, the German states and Ferdinand agreed to the Peace of Prague. In return for withdrawing the Edict of Restitution, the Heilbronn and Catholic Leagues agreed to dissolve their forces, which 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 war ceased to be a primarily inter-German religious conflict.

In March 1635, French soldiers entered the Valtellina, cutting the link between Milan and the Empire. This was followed in May by an invasion of the Spanish Netherlands, which collapsed with the loss of 17,000 men. In March 1636, France joined the Thirty Years' War as an ally of Sweden, which was increasingly reliant on French financing for its continued participation. The Spanish responded by invading northern France, causing panic in Paris before lack of supplies forced them to retreat. Elsewhere, Saxony began the year by occupying Pomerania, before defeats at Dömitz and Wittstock in October re-established Swedish predominance in northeast Germany.

Ferdinand II died in February 1637, and was succeeded by his son Ferdinand III, who faced a precarious military position. Although Matthias Gallas had forced Johan Banér, the new Swedish commander, back to the Baltic, in March 1638 Bernard of Saxe Weimar destroyed an Imperial army at Rheinfelden. His capture of Breisach in December severed the Spanish Road, while Charles I Louis raised an army to regain his father's possessions in the Palatinate. Although the latter was routed by von Hatzfeldt at Vlotho in October, lack of supplies obliged Gallas to withdraw from the Baltic.

In April 1639, Banér defeated the Saxons at Chemnitz, then invaded Bohemia in May. To retrieve the situation, Ferdinand diverted Piccolomini's army from Thionville, ending direct military cooperation between Austria and Spain. Pressure grew on Olivares to make peace, especially after French and Swedish gains in Germany cut the Spanish Road, forcing Spain to resupply their armies in Flanders by sea. Attempts to re-assert maritime control ended when the Dutch fleet under Maarten Tromp won a significant victory over the Spanish at the Downs in October 1639.

The French occupied Spanish-controlled Artois in 1640, while Dutch attacks on Portuguese colonies, combined with opposition to taxes, led to revolts in both Portugal and Catalonia. Olivares now argued Spain should accept Dutch independence, and focus on preventing further French gains in the Spanish Netherlands. This appeared achievable since most of the Dutch regenten believed the war was won, the only question being the price of peace. They therefore reduced the army budget for 1640, despite objections from Frederick Henry.

After Bernard died in July 1639, his troops joined Banér's Swedish army in an ineffectual campaign along the Weser, the highlight being a surprise attack in January 1641 on the Imperial Diet in Regensburg. Forced to retreat, Banér reached Halberstadt in May where he died, and despite beating off an Imperial force at Wolfenbüttel in June, his largely German troops mutinied due to lack of pay. The situation was saved by the arrival of Lennart Torstensson in November with 7,000 Swedish recruits and enough cash to satisfy the mutineers.

The French won a victory at Kempen with Hessian support in January 1642. This was followed by a Swedish victory at Breitenfeld in October 1642, where Torstensson inflicted almost 10,000 casualties on an Imperial army led by Archduke Leopold Wilhelm of Austria. The Swedes captured Leipzig in December, although they failed to take Freiberg, and by 1643 the Saxon army had been reduced to a few isolated garrisons. Despite these setbacks, Ferdinand fought on, hoping to improve his position enough to exclude the Imperial Estates from his peace negotiations with France and Sweden, and allow him to represent the Empire as a whole.

This seemed more likely when Richelieu died in December 1642, followed by Louis XIII in May 1643, leaving his five-year-old son Louis XIV as king. However, Richelieu's policies were continued by his successor Cardinal Mazarin, while gains in Alsace allowed France to focus on the war against Spain. In 1643, the Army of Flanders invaded northern France, but were decisively beaten by Condé at Rocroi on 19 May. This ended any prospect of re-opening the Spanish Road, and Madrid finally accepted the reality of Dutch independence.

However, Condé was unable to fully exploit his victory due to factors affecting all combatants. The devastation inflicted by 25 years of warfare meant armies spent more time foraging than fighting, forcing them to become smaller and more mobile, with a much greater emphasis on cavalry. Difficulties in gathering provisions meant campaigns started later, and restricted them to areas that could be easily supplied, usually close to rivers. In addition, the French army in Germany was shattered at Tuttlingen in November by Bavarian general Franz von Mercy.

Soon after Rocroi, Ferdinand invited Sweden and France to attend peace talks in the Westphalian towns of Münster and Osnabrück, but negotiations 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 Torstensson War began when the Swedes invaded Jutland with Dutch naval support. The Swedish attack on Jutland, commanded by Torstensson, was accompanied by another invasion through Scania, led by Gustav Horn. Ferdinand assembled an army under Gallas to attack the Swedes from the rear and to support Denmark, which proved a disastrous decision. Leaving Wrangel to finish the war in Denmark, in May 1644 Torstensson marched back into Germany. Gallas was unable to stop him, and the Danes sued for peace after their defeat at Fehmarn in October 1644.

In August 1644, the French and Bavarian armies met in the three day Battle of Freiburg, in which both sides suffered heavy casualties. Convinced the war could no longer be won, Maximilian now put pressure on Ferdinand to end the conflict. Shortly after peace talks restarted in November, Gallas' army disintegrated and the remnants retreated into Bohemia, where they were scattered by Torstensson at Jankau in March 1645. In May, Bavarians under von Mercy destroyed a French detachment at Herbsthausen, before he in turn was defeated and killed at Second Nördlingen in August. In September, John George of Saxony signed a six-month truce with Sweden, then agreed to remain neutral in the March 1646 Treaty of Eulenberg.

Under Turenne, French commander in the Rhineland, and Wrangel, who had replaced Torstensson, the French and Swedes separately invaded Bavaria in the summer of 1646. Maximilian was soon desperate to end the war he was largely responsible for starting, at which point the Spanish publicised a secret offer by Mazarin to exchange French-occupied Catalonia for the Spanish Netherlands. Angered by this duplicity, the Dutch agreed a truce with Spain in January 1647 and began to negotiate their own peace terms. Having failed to acquire the Netherlands through diplomacy, Mazarin decided to do so by force. To free up resources for the attempt, on 14 March 1647 he signed the Truce of Ulm with Bavaria, Cologne and Sweden.

The planned offensive fell apart when Turenne's mostly German troops mutinied, while Bavarian general Johann von Werth refused to comply with the truce. Although the mutinies were quickly suppressed, Maximilian felt obliged to follow Werth's example, and in September ordered Bronckhorst-Gronsfeld to combine the remnants of the Bavarian army with Imperial troops under Peter von Holzappel. Outnumbered by a Franco-Swedish army led by Wrangel and Turenne, they were defeated at Zusmarshausen in May 1648. Holzappel was killed, and although most of his army escaped thanks to Raimondo Montecuccoli, Bavaria was left defenceless once again.

The Swedes sent a second force under von Königsmarck to attack 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 treasures including the Codex Gigas, which can now be seen in Stockholm. When a Spanish offensive in Flanders ended with defeat at Lens in August 1648, Ferdinand finally agreed terms and on 24 October, he signed peace treaties with France and Sweden, ending the war.

Italy

Control of Northern Italy provided access to the vulnerable southern borders of France and Austria. It also contained large sections of the Spanish Road, which allowed Spain to safely move recruits from Italy to support their war in the Netherlands. The French sought to disrupt this vital supply route by attacking the Spanish-held Duchy of Milan, or blocking the Alpine passes.

In 1618, war broke out in the Valtellina between the Catholic Grisons Rebels and the Protestant Three Leagues. Both Spain and France sent troops to support different factions, with France sending the Duke of Rohan and Spain the Duke of Feria. In 1625, Savoy invaded Genoa with French support, while François d'Estrées invaded the Valtellina. Spain then sent the Duke of Feria and the Marquess of Santa Cruz to relieve Genoa, which happened in April 1625. In 1626, France and Spain signed the Treaty of Monzón, with France agreeing to withdraw from the Valtellina and Piedmont.

Montferrat and its fortress of Casale Monferrato were subsidiary territories of the Duchy of Mantua and their possession allowed the holder to threaten Milan. When the Duke of Mantua died in December 1627, France and Spain backed rival claimants, resulting in the 1628 to 1631 War of the Mantuan Succession. The French-born Duke of Nevers was backed by France and the Republic of Venice, his rival the Duke of Guastalla by Spain, Ferdinand II, Savoy and Tuscany. While a relatively minor conflict, the struggle had a disproportionate impact on the Thirty Years War, since Pope Urban VIII viewed Habsburg expansion in Italy as a threat to the Papal States. His opposition to Ferdinand II divided the Catholic powers, and made it acceptable for France to employ Protestant allies against Austria.

In March 1629, the French stormed Savoyard positions in the Pas de Suse, lifted the Spanish siege of Casale, and captured Pinerolo. The Treaty of Suza then ceded the two fortresses to France and allowed their troops unrestricted passage through Savoyard territory, giving them control over Piedmont and the Alpine passes into southern France. However, as soon as the main French army withdrew in late 1629, the Spanish and Savoyards besieged Casale once again. At the same time, mercenaries funded by Ferdinand II were used in a Spanish offensive which routed the main Venetian field army, and forced Nevers to abandon Mantua. By October 1630, the French position seemed so precarious their representatives agreed the Treaty of Ratisbon. It was never ratified, as Richelieu claimed he had not approved the terms.

Several factors restored the French position in northern Italy, notably a devastating outbreak of plague; between 1629 and 1631, over 60,000 died in Milan and 46,000 in Venice, with proportionate losses elsewhere. Richelieu took advantage of the diversion of imperial resources to fund a Swedish invasion of Germany, whose success forced the Spanish-Savoyard alliance to withdraw from Casale and sign the Treaty of Cherasco in April 1631. Nevers was confirmed as Duke of Mantua and 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.

After the outbreak of the Franco–Spanish War in 1635, Richelieu supported a renewed offensive by Victor Amadeus against Milan to tie down Spanish resources. These included an unsuccessful attack on Valenza in 1635, plus minor victories at Tornavento and Mombaldone. However, the anti-Habsburg alliance in northern Italy fell apart when first Charles of Mantua died in September 1637, then Victor Amadeus in October, whose death led to a struggle for control of the Savoyard state between his widow Christine of France and brothers, Thomas and Maurice.

In 1639, their quarrel erupted into open warfare, with France backing Christine and Spain the two brothers, and resulted in the Siege of Turin. One of the most famous military events of the 17th century, at one stage it featured no less than three different armies besieging each other. However, revolts in Portugal and Catalonia forced the Spanish to cease operations in Italy, and the war was settled on terms favourable to Christine and France.

In 1647, a French-backed rebellion succeeded in temporarily overthrowing Spanish rule in Naples. The Spanish quickly crushed the Neapolitan Revolt of 1647 and restored their rule over all of southern Italy, defeating multiple French expeditionary forces sent to back the rebels. However, it exposed the weakness of Spanish rule in Italy and the alienation of the local elites from Madrid. In 1650, the governor of Milan wrote that as well as widespread dissatisfaction in the south, the only one of the Italian states that could be relied on was the Duchy of Parma.

Iberian Peninsula

Throughout the 1630s, tax increases levied to pay for the war led to protests throughout Spanish territories, which in 1640 resulted in revolts: first in Portugal with the Restoration War to re-gain their independence against the Iberian Union, then in the Principality of Catalonia. Both were backed by France as part of Richelieu's 'war by diversion', in January 1641 the rebels proclaimed a Catalan Republic. The Madrid government quickly assembled an army of 26,000 men to crush the Catalan revolt, which defeated the rebels at Martorell on 23 January 1641. The French now persuaded the Catalan Courts to recognise Louis XIII as Count of Barcelona, and ruler of Catalonia.

On 26 January, a combined French-Catalan force routed a larger Spanish army at Montjuïc and 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 current-day Franco-Spanish border in the Pyrenees. The revolt ended in 1651 when Madrid recaptured Barcelona.

Peace of Westphalia

In its final form, the Peace of Westphalia consisted of three separate agreements. These were the Peace of Münster between Spain and the Dutch Republic, the Treaty of Osnabrück between the Empire and Sweden, and the Treaty of Münster between the Empire and France. Split between Münster and Osnabrück, talks began in 1642, with a total of 109 delegations attending at one time or other. After the Swedes rejected Christian of Denmark as mediator, the negotiators finally agreed on Papal Legate Fabio Chigi, and Venetian envoy Alvise Contarini.

The first to be signed on 30 January 1648, the Peace of Münster forms part of the Westphalia settlement since the Dutch Republic was still considered imperial territory. It confirmed Dutch independence from Spain, although the Republic was not officially acknowledged as being outside the Empire until 1728. The Dutch also gained a monopoly over trade conducted through the Scheldt estuary, ensuring the commercial ascendancy of Amsterdam. Antwerp, capital of the Spanish Netherlands and previously the most important port in northern Europe, would not recover economically until the late 19th century.

The terms of the separate treaties with France and Sweden had first to be agreed by Ferdinand and the Imperial Estates. It has been argued they were a "major turning point in German and European...legal history", because they went beyond normal peace settlements and effected major constitutional and religious changes to the Empire itself. Negotiations were complex and slow, with states like Saxony and Bavaria having very different views on desired outcomes. Ferdinand delayed signing, hoping for an improvement in his military position, but with Swedish troops on the verge of taking Prague, he finally did so on 24 October.

Key elements of the Peace were provisions confirming the autonomy of states within the Empire, Ferdinand's acceptance of the supremacy of the Imperial Diet, and those seeking to prevent future religious conflict. Article 5 reconfirmed the Augsburg settlement, established 1624 as the basis, or "Normaljahr", for determining the dominant religion of a state and guaranteed freedom of worship for religious minorities. Article 7 recognised Calvinism as a Reformed faith and removed the ius reformandi, the requirement that if a ruler changed his religion, his subjects had to follow suit. These terms did not apply to the hereditary lands of the Habsburg monarchy, such as Lower and Upper Austria.

In terms of territorial concessions, 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. 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 the Prince-bishoprics of Bremen and Verden, which also gave them a seat in the Imperial Diet.

The terms were denounced by Pope Innocent X, for whom the bishoprics ceded to France and Brandenburg were 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 Protestant strongholds prior to 1618. Fighting did not end immediately, since demobilising over 200,000 soldiers took time, and the last Swedish garrison did not leave Germany until 1654. In addition, 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 Poland–Lithuania 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 "Congress" model was used for negotiations at Aix-la-Chapelle in 1668, Nijmegen in 1678, and Ryswick in 1697, although unlike the 19th-century system, these were intended to end wars, rather than prevent them.

Human and financial cost of the war

The Thirty Years' War is part of what historians sometimes call "The General Crisis" of the mid-17th century, a period of sustained conflict and unrest in areas ranging from Ming China to the British Isles, Tsarist Russia and the Holy Roman Empire. In each of these, fighting combined with famine and disease to inflict severe losses on local civilian populations. While the war certainly ranks as one of the worst of these events, 19th-century German nationalists often exaggerated its impact to illustrate the dangers of a divided Germany.

Claims of up to 12 million deaths from a population of 18 million are no longer considered realistic, while upper estimates of material losses are not supported by contemporary evidence, or in some cases exceed prewar tax records. Regardless, modern commentators agree the war was a man-made mortality disaster previously unknown in Europe. Estimates of total deaths range from 4.5 to 8 million, most incurred after 1630 when Sweden entered the war, the vast majority being civilians.

Battles generally featured armies of around 13,000 to 20,000 each, one of the largest being Alte Veste in 1632 with a combined 70,000 to 85,000. Estimates of total combatants deployed by both sides within Germany range from an average of 80,000 to 100,000 from 1618 to 1626, peaking at 250,000 in 1632 and falling to under 160,000 by 1648.

Casualty rates for those who served in the military could be extremely high. Of 230 men conscripted from the Swedish village of Bygdeå between 1621 and 1639, 215 are recorded as dead or missing, while another 5 returned home crippled. Historian Peter Wilson puts those killed or wounded in action at around 450,000. Research shows disease increased that number by a factor of between two and three, which suggests total military casualties ranged from 1.3 to 1.8 million. Although his methodology has been disputed, sociologist Pitirim Sorokin estimates 2,071,000 military deaths, of which 1,151,000 occurred between 1635 and 1648.

Local returns show only 3% of civilian deaths were due to military action, the major causes being starvation (12%), bubonic plague (64%), typhus (4%), and dysentery (5%). Poor harvests throughout the 1630s and repeated plundering of the same areas led to widespread famine, with reports of people eating grass, too weak to accept alms, or resorting to cannibalism. Although regular outbreaks of disease were common prior to 1618, their spread was accelerated by the influx of foreign soldiers, the shifting locations of battle fronts, and displacement of rural populations into already crowded cities. Soldiers transferred from Germany allegedly sparked the 1629–1631 Italian plague, described as the "worst mortality crisis to affect Italy during the early modern period". This resulted in some 280,000 deaths, with estimates of up to a million.

Modern historians generally agree that the German areas of the Holy Roman Empire experienced an overall population decline of roughly 40%, from 18 and 20 million in 1600 to between 11 and 13 million in 1650, and did not regain pre-war levels until 1750. Nearly 50% of these losses were incurred during the first period of Swedish intervention from 1630 to 1635. The Czech lands also saw a 27% population decline, from approximately 2.95 million in 1600 to 2.15 million in 1650. The high mortality rate was partly 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, historian Günther Franz published an analysis of data from across Germany covering the period from 1618 to 1648. Broadly confirmed by more recent work, he concluded about 40% of the civilian rural population became casualties, and 33% of the urban. These figures need to be read with care, 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. There were also wide regional variations, with areas of northwest Germany experiencing minimal loss of population, while those of Mecklenburg, Pomerania and Württemberg fell by nearly 50%.

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, especially in the period 1618 to 1623, 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.

Military developments

Innovations made by Gustavus in particular are considered part of the evolution known as the "Military Revolution", although whether tactics or technology were at the heart of these changes is still debated. Introduced by Maurice of Orange in the 1590s, these sought to increase infantry firepower by moving from massed columns to line formation. Gustavus further reduced the ten ranks used by Maurice to six, and increased the proportion of musketeers to pikemen. He also enhanced their firepower by providing each unit with quick-firing light artillery pieces on either flank. The best example of their application in battle was the victory over Tilly's traditionally organised army at Breitenfeld in September 1631.

Line formations were often harder to co-ordinate, as demonstrated when the supposedly obsolete Spanish tercios defeated the Swedes at Nördlingen in 1634. Since they also lacked the offensive impact of columns, Gustavus compensated by requiring his cavalry to be far more aggressive, often employing Finnish Hakkapeliitta as shock troops. However, even the Swedes used columns on occasion, notably the failed assault at Alte Veste in September 1632. The line versus column debate continued into the early 19th century, and both were employed during the Napoleonic Wars.

Such tactics needed professional soldiers, who could retain formation, reload and fire disciplined salvos while under attack, as well as the use of standardised weapons. The first half of the 17th century saw the publication of numerous instruction manuals showing the movements required, thirty-two for pikemen and forty-two for musketeers. In theory, it took up to six months to train infantry to operate in this way, but in reality many went into battle with far less experience. It also placed greater responsibility on junior officers who provided the vital links between senior commanders and the tactical unit. One of the first military schools designed to produce such men was set up at Siegen in 1616, and others soon followed.

On the other hand, strategic thinking failed to develop at the same pace. Historian Jeremy Black claims most campaigns were "inconclusive", since they were primarily concerned with gaining access to supplies and money for the soldiers, rather than focused strategic objectives. The disconnect between military and diplomatic goals helps explain why the war lasted so long, and peace proved so elusive. When fighting officially ended in 1648, there were still over 150,000 troops under arms within the Empire, small numbers by modern standards, but unprecedented at the time. Most 17th-century states could not finance armies of this size for extended periods, forcing them to depend on "contributions" from areas they passed through.

Supplies thus became the limiting factor in planning campaigns, a problem that grew more acute as the war progressed. Armies became smaller, with a greater emphasis on cavalry that could cover greater distances and move faster, rather than slow moving infantry. Poor infrastructure also required commanders to stay close to rivers, then the primary means of bulk transportation, and meant they could not move too far from their main bases. Feeding the troops became an objective in itself, unconnected to diplomatic goals and largely uncontrolled by their central governments. The result was "armies increasingly devoid of intelligible political objectives...degenerating into travelling armed mobs, living in a symbiotic relationship with the countryside they passed through". This often conflicted with the political aims of their employers; the devastation inflicted in 1628 and 1629 by imperial troops on Brandenburg and Saxony, both nominally allies, was a major factor in their support for Swedish intervention.

Finally, some commentators argue that while the Thirty Years' War certainly played a role in accelerating the development of new tactics and technology, the need to fund, supply, and direct permanent armies for extended periods across wide-ranging theatres was of greater significance. This required much more sophisticated mechanisms and led to the transfer of organised violence from "contractor" generals like Wallenstein or Mansfeld to nation-states. In this sense, the truly "revolutionary" aspect of the Military Revolution was less about the tactics and technology used by soldiers and more about the institutions required to support them.

Social and cultural 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 ecosystem. Food shortages were worsened by an explosion in the rodent population, while Bavaria was overrun by wolves in the winter of 1638, and 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 relentless and often random bloodshed unleashed by the war. Attributed by religious authorities to divine retribution, attempts to identify a supernatural cause led to a series of witch-hunts, starting in Franconia in 1626, then quickly spreading to other parts of Germany. They began 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.

The Bamberg witch trials, held in the nearby Bishopric of Bamberg from 1626 to 1631, claimed over one thousand lives; in 1629, 274 died in the Eichstätt witch trials, 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. However, the extent to which they were symptomatic of the impact of the conflict on society is debatable, since many took place in areas relatively untouched by the war. Concerned their brutality would discredit the Counter-Reformation, Ferdinand ensured active persecution largely ended by 1630.

Although the war caused immense destruction, it has also been credited with sparking a revival in German literature, including the creation of societies dedicated to "purging foreign elements" from the German language. One example is Simplicius Simplicissimus, a picaresque novel written by Hans Jakob Christoffel von Grimmelshausen in 1668, providing a realistic portrayal of a soldier's life based on his own experience, which is verified by other sources. Other less famous examples include the diaries of Peter Hagendorf, a participant in the Sack of Magdeburg whose descriptions of the everyday brutalities of the war remain compelling.

For German, and to a lesser extent Czech writers, the war was remembered as a defining moment of national trauma, the 18th-century poet and playwright Friedrich Schiller being one of many to use it in their work. Variously known as the 'Great German War,' 'Great War', or 'Great Schism', for 19th- and early 20th-century German nationalists it showed the dangers of a divided Germany and was used to justify the creation of the German Empire in 1871, as well as the Greater Germanic Reich envisaged by the Nazis. Bertolt Brecht used it as the backdrop for his 1939 anti-war play Mother Courage and Her Children, while its enduring cultural resonance is illustrated by the novel Tyll; written by Austro-German author Daniel Kehlmann and also set during the war, it was nominated for the 2020 Booker Prize.

Political consequences

The Peace of Westphalia reconfirmed "German liberties", ending Habsburg attempts to convert the Holy Roman Empire into a centralised state similar to Spain. Over the next 50 years, Bavaria, Brandenburg-Prussia, Saxony, and others increasingly pursued 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. They also became a far more coherent geographical bloc with the addition of Bohemia, and the restoration of Catholicism throughout their territories.

By laying the foundations of the modern nation state, the Peace of Westphalia changed the relationship between rulers and ruled, many of whom previously had multiple political and religious allegiances. After 1648, they were now understood to be subject first and foremost to the laws and edicts of their respective state authority, not the claims of any other entity, either religious or secular. This made it easier to levy national forces loyal to the state and its leader; one lesson learned from Wallenstein and the Swedish invasion was the need for their own permanent armies, and German society became far more militarised.

For Sweden, the war had established the kingdom as a major force in Northern Europe, but the direct benefits of the Peace of Westphalia ultimately 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 provided both seats and influence in the Imperial Diet, it also brought Sweden into direct conflict with Brandenburg–Prussia and Saxony, their competitors in Pomerania. The income from their German possessions was relatively minor, and although parts of Pomerania remained Swedish until 1815, much of it was ceded to Prussia in 1679 and 1720.

France arguably gained more from the conflict than any other power, and by 1648, most of Richelieu's objectives had been achieved. These included separation of the Spanish and Austrian Habsburgs, expansion of the French frontier into the Holy Roman Empire, and an end to Spanish military supremacy in Northern Europe. Although the Franco–Spanish war continued until 1659, the Peace of Westphalia allowed Louis XIV to begin replacing Spain as the predominant European power.

While religion remained a divisive political issue in many countries, the Thirty Years' War is arguably the last major European conflict where it was a primary driver. Future religious conflicts were either internal, such as the Camisards revolt in southern France, or relatively minor, like the 1712 Toggenburg War. The war created the outlines of a Europe that persisted until 1815 and beyond, most significantly the nation-state of France, along with the start of a split between Germany and a separate Austro-Hungarian bloc.