Thirty Years' War

The Thirty Years' War (1618–1648) was a series of wars principally fought in Central Europe, involving most of the countries of Europe. It was one of the longest and most destructive conflicts in European history, and one of the longest continuous wars in modern history.

The origins of the conflict and goals of the participants were complex and no single cause can accurately be described as the main reason for the fighting. Initially, it was fought largely as a religious war between Protestants and Catholics in the Holy Roman Empire, although disputes over internal politics and the balance of power within the Empire played a significant part. Gradually, it developed into a more general conflict involving most of the great powers of the time. In this general phase the war became less specifically religious and more a continuation of the Bourbon–Habsburg rivalry for European political pre-eminence, leading in turn to further warfare between France and the Habsburg powers.

A major consequence of the Thirty Years' War was the devastation of entire regions, denuded by the foraging armies (bellum se ipsum alet). Famine and disease significantly decreased the population of the German states, Bohemia, the Low Countries, and Italy; most of the combatant powers were bankrupted. While the regiments within each army were not strictly mercenary, in that they were not units for hire that changed sides from battle to battle, some individual soldiers that made up the regiments were mercenaries. The problem of discipline was made more difficult by the ad hoc nature of 17th-century military financing; armies were expected to be largely self-funding, by means of loot taken or tribute extorted from the settlements where they operated. This encouraged a form of lawlessness that imposed severe hardship on inhabitants of the occupied territory.

The Thirty Years' War was ended with the treaties of Osnabrück and Münster, part of the wider Peace of Westphalia. Some of the quarrels that provoked the war went unresolved for a much longer time.

Origins of the War
The Peace of Augsburg (1555), signed by Charles V, Holy Roman Emperor, confirmed the result of the 1526 Diet of Speyer, ending the war between German Lutherans and Catholics, and establishing that: Although the Peace of Augsburg created a temporary end to hostilities, it did not resolve the underlying religious conflict, which was made yet more complex by the spread of Calvinism throughout Germany in the years that followed. This added a third major faith to the region, but its position was not recognized in any way by the Augsburg terms, to which only Catholicism and Lutheranism were parties.
 * Rulers of the 224 German states could choose the religion (Lutheranism or Catholicism) of their realms according to their consciences, and compel their subjects to follow that faith (the principle of cuius regio, eius religio).
 * Lutherans living in a prince-bishopric (a state ruled by a Catholic bishop) could continue to practice their faith.
 * Lutherans could keep the territory they had captured from the Catholic Church since the Peace of Passau in 1552.
 * Those prince-bishops who had converted to Lutheranism were required to give up their territories (the principle called reservatum ecclesiasticum).

The rulers of the nations neighboring the Holy Roman Empire also contributed to the outbreak of the Thirty Years' War:
 * Spain was interested in the German states because it held the territories of the Spanish Netherlands in the western part of the Empire and states within Italy which were connected by land through the Spanish Road. The Dutch revolted against the Spanish domination during the 1560s, leading to a protracted war of independence that led to a truce only in 1609.
 * France was nearly surrounded by territory controlled by the two Habsburg states (Spain and the Holy Roman Empire), and was eager to exert its power against the weaker German states; this dynastic concern overtook religious ones and led to Catholic France's participation on the otherwise Protestant side of the war.
 * Sweden and Denmark were interested in gaining control over northern German states bordering the Baltic Sea.

The Holy Roman Empire was a fragmented collection of largely independent states. The position of the Holy Roman Emperor was mainly titular, but the emperors, from the House of Habsburg, also directly ruled a large portion of Imperial territory (the Archduchy of Austria and the Kingdom of Bohemia) as well as the Kingdom of Hungary. The Austrian domain was thus a major European power in its own right, ruling over some eight million subjects. The House of Habsburg, under a second King, also ruled Spain, including the Spanish Netherlands, south Italy, the Philippines and most of the Americas. The Empire also contained several regional powers, such as the Duchy of Bavaria, the Electorate of Saxony, the Margraviate of Brandenburg, the Electorate of the Palatinate, Landgraviate of Hesse, the Archbishopric of Trier and the Free Imperial City of Nuremberg (containing from 500,000 to one million inhabitants). A vast number of minor independent duchies, free cities, abbeys, prince-bishoprics, and petty lordships (whose authority sometimes extended to no more than a single village) rounded out the Empire. Apart from Austria and perhaps Bavaria, none of those entities was capable of national-level politics; alliances between family-related states were common, due partly to the frequent practice of splitting a lord's inheritance among the various sons.

Religious tensions remained strong throughout the second half of the 16th century. The Peace of Augsburg began to unravel, as some converted bishops refused to give up their bishoprics, and as certain Habsburg and other Catholic rulers of the Holy Roman Empire and Spain sought to restore the power of Catholicism in the region. This was evident from the Cologne War (1583–88), a conflict initiated when the prince-archbishop of the city, Gebhard Truchsess von Waldburg, converted to Calvinism. As he was an imperial elector, this could have produced a Protestant majority in the College that elected the Holy Roman Emperor – a position that had always been held by a Catholic.

In the Cologne War, Spanish troops expelled the former prince-archbishop and replaced him with Ernst of Bavaria, a Roman Catholic. After this success, the Catholics regained peace, and the principle of cuius regio, eius religio began to be exerted more strictly in Bavaria, Würzburg and other states. This forced Lutheran residents to choose between conversion or exile. Lutherans also witnessed the defection of the lords of the Palatinate (1560), Nassau (1578), Hesse-Kassel (1603) and Brandenburg (1613) to the new Calvinist faith. Thus, at the beginning of the 17th century, the Rhine lands and those south to the Danube were largely Catholic, while Lutherans predominated in the north, and Calvinists dominated in certain other areas, such as west-central Germany, Switzerland and the Netherlands. However, minorities of each creed existed almost everywhere. In some lordships and cities, the number of Calvinists, Catholics, and Lutherans were approximately equal.

Much to the consternation of their Spanish ruling cousins, the Habsburg emperors who followed Charles V (especially Ferdinand I and Maximilian II, but also Rudolf II, and his successor Matthias) were content for the princes of the Empire to choose their own religious policies. These rulers avoided religious wars within the empire by allowing the different Christian faiths to spread without coercion. This angered those who sought religious uniformity. Meanwhile, Sweden and Denmark, both Lutheran kingdoms, sought to assist the Protestant cause in the Empire, and wanted to gain political and economic influence there as well.

Religious tensions broke into violence in the German free city of Donauwörth in 1606. There, the Lutheran majority barred the Catholic residents of the Swabian town from holding an annual Markus procession, which provoked a riot. This prompted foreign intervention by Duke Maximilian of Bavaria (1573–1651) on behalf of the Catholics. After the violence ceased, Calvinists in Germany (who remained a minority) felt the most threatened. They banded together and formed the League of Evangelical Union in 1608, under the leadership of the Elector Palatine Frederick IV (1583–1610), (whose son, Frederick V, married Elizabeth Stuart, the daughter of James I of England). The establishment of the League prompted the Catholics into banding together to form the Catholic League in 1609, under the leadership of Duke Maximilian.

Tensions escalated further in 1609, with the War of the Jülich succession, which began when John William, Duke of Jülich-Cleves-Berg, the ruler of the strategically important United Duchies of Jülich-Cleves-Berg, died childless. There were two rival claimants to the duchy. The first was Duchess Anna of Prussia, daughter of Duke John William's eldest sister, Marie Eleonore of Cleves. Anna was married to John Sigismund, Elector of Brandenburg. The second was Wolfgang William, Count Palatine of Neuburg, who was the son of Duke John William's second eldest sister, Anna of Cleves. Duchess Anna of Prussia claimed Jülich-Cleves-Berg as the heir to the senior line, while Wolfgang William, Count Palatine of Neuburg claimed Jülich-Cleves-Berg as Duke John William's eldest male heir. Both claimants were Protestants. In 1610, to prevent war between the rival claimants, the forces of Rudolf II, Holy Roman Emperor occupied Jülich-Cleves-Berg until the dispute was decided by the Aulic Council (Reichshofrat). However, several Protestant princes feared the Emperor, a devout Catholic, intended to keep Jülich-Cleves-Berg for himself to prevent the United Duchies falling into Protestant hands. Representatives of Henry IV of France and the Dutch Republic gathered forces to invade Jülich-Cleves-Berg, but these plans were cut short by the assassination of Henry IV. Hoping to gain an advantage in the dispute, Wolfgang William converted to Catholicism; John Sigismund, on the other hand, converted to Calvinism (although Anna of Prussia stayed Lutheran). The dispute was settled in 1614 with the Treaty of Xanten, by which the United Duchies were dismantled: Jülich and Berg were awarded to Wolfgang William, while John Sigismund gained Cleves, Mark, and Ravensberg.

The background of the Dutch Revolt is also necessary to understanding the events leading up to the Thirty Years' War. It was widely known that the Twelve Years' Truce was set to expire in 1621, and throughout Europe it was recognized that at that time, Spain would attempt to reconquer the Dutch Republic. At that time, forces under Ambrogio Spinola, 1st Marquis of the Balbases, the Genoese commander of the Spanish army, would be able to pass through friendly territories to reach the Dutch Republic; the only hostile state that stood in his way was the Electorate of the Palatinate. (Spinola's preferred route would take him through the Republic of Genoa, the Duchy of Milan, through the Val Telline, around hostile Switzerland bypassing along the north shore of Lake Constance, then through Alsace, the Archbishopric of Strasbourg, then through the Electorate of the Palatinate, and then finally through the Archbishopric of Trier, Jülich and Berg and on to the Dutch Republic). The Palatinate thus assumed a strategic importance in European affairs out of all proportion to its size. This explains why the Protestant James I of England arranged for the marriage of his daughter Elizabeth Stuart to Frederick V, Elector Palatine in 1612, in spite of the social convention that a princess would only marry another royal.

By 1617, it was apparent that Matthias, Holy Roman Emperor and King of Bohemia, would die without an heir, with his lands going to his nearest male relative, his cousin Archduke Ferdinand II of Austria, heir-apparent and Crown Prince of Bohemia. With the Oñate treaty, Philip III of Spain agreed to this succession.

Ferdinand, having been educated by the Jesuits, was a staunch Catholic who wanted to impose religious uniformity on his lands. This made him highly unpopular in Protestant (primarily Hussite) Bohemia. The population's sentiments notwithstanding, the added insult of the nobility's rejection of Ferdinand, who had been elected Bohemian Crown Prince in 1617, triggered the Thirty Years' War in 1618, when his representatives were thrown out of a window and seriously injured. The so-called Defenestration of Prague provoked open revolt in Bohemia, which had powerful foreign allies. Ferdinand was upset by this calculated insult, but his intolerant policies in his own lands had left him in a weak position. The Habsburg cause in the next few years would seem to suffer unrecoverable reverses. The Protestant cause seemed to wax toward a quick overall victory.

The war can be divided into 4 major phases: The Bohemian Revolt, the Danish intervention, the Swedish intervention and the French intervention.

1618–1621
Without heirs, Emperor Matthias sought to assure an orderly transition during his lifetime by having his dynastic heir (the fiercely Catholic Ferdinand of Styria, later Ferdinand II, Holy Roman Emperor) elected to the separate royal thrones of Bohemia and Hungary. Some of the Protestant leaders of Bohemia feared they would be losing the religious rights granted to them by Emperor Rudolf II in his Letter of Majesty (1609). They preferred the Protestant Frederick V, elector of the Palatinate (successor of Frederick IV, the creator of the Protestant Union). However, other Protestants supported the stance taken by the Catholics, and in 1617, Ferdinand was duly elected by the Bohemian Estates to become the Crown Prince, and automatically upon the death of Matthias, the next King of Bohemia.

The king-elect then sent two Catholic councillors (Vilem Slavata of Chlum and Jaroslav Borzita of Martinice) as his representatives to Hradčany castle in Prague in May 1618. Ferdinand had wanted them to administer the government in his absence. On 23 May 1618, an assembly of Protestants seized them and threw them (and also secretary Philip Fabricius) out of the palace window, which was some 21 m off the ground. Remarkably, although wounded, they survived. This event, known as the (Second) Defenestration of Prague, started the Bohemian Revolt. Soon afterward, the Bohemian conflict spread through all of the Bohemian Crown, including Bohemia proper, Silesia, Upper and Lower Lusatia, and Moravia. Moravia was already embroiled in a conflict between Catholics and Protestants. The religious conflict eventually spread across the whole continent of Europe, involving France, Sweden, and a number of other countries.

Had the Bohemian rebellion remained a local conflict, the war could have been over in fewer than thirty months. However, the death of Emperor Matthias emboldened the rebellious Protestant leaders, who had been on the verge of a settlement. The weaknesses of both Ferdinand (now officially on the throne after the death of Emperor Matthias) and of the Bohemians themselves led to the spread of the war to western Germany. Ferdinand was compelled to call on his nephew, King Philip IV of Spain, for assistance.

The Bohemians, desperate for allies against the Emperor, applied to be admitted into the Protestant Union, which was led by their original candidate for the Bohemian throne, the Calvinist Frederick V, Elector Palatine. The Bohemians hinted Frederick would become King of Bohemia if he allowed them to join the Union and come under its protection. However, similar offers were made by other members of the Bohemian Estates to the Duke of Savoy, the Elector of Saxony, and the Prince of Transylvania. The Austrians, who seemed to have intercepted every letter leaving Prague, made these duplicities public. This unraveled much of the support for the Bohemians, particularly in the court of Saxony. The rebellion initially favoured the Bohemians. They were joined in the revolt by much of Upper Austria, whose nobility was then chiefly Lutheran and Calvinist. Lower Austria revolted soon after, and in 1619, Count Thurn led an army to the walls of Vienna itself.

Ottoman support
In the east, the Protestant Hungarian Prince of Transylvania, Gabriel Bethlen, led a spirited campaign into Hungary with the support of the Ottoman Sultan, Osman II. Fearful of the Catholic policies of Ferdinand II, Gabriel Bethlen requested a protectorate by Osman II, so "the Ottoman Empire became the one and only ally of great-power status which the rebellious Bohemian states could muster after they had shaken off Habsburg rule and had elected Frederick V as a Protestant king". Ambassadors were exchanged, with Heinrich Bitter visiting Constantinople in January 1620, and Mehmed Aga visiting Prague in July 1620. The Ottomans offered a force of 60,000 cavalry to Frederick and plans were made for an invasion of Poland with 400,000 troops in exchange for the payment of an annual tribute to the Sultan. These negotiations triggered the Polish–Ottoman War of 1620–21. The Ottomans defeated the Poles, who were supporting the Habsburgs in the Thirty Years' War, at the Battle of Cecora in September–October 1620, but were not able to further intervene efficiently before the Bohemian defeat at the Battle of the White Mountain in November 1620. Later Poles defeated the Ottomans at the Battle of Chocim and the war ended with status quo.

The emperor, who had been preoccupied with the Uskok War, hurried to muster an army to stop the Bohemians and their allies from overwhelming his country. Count Bucquoy, the commander of the Imperial army, defeated the forces of the Protestant Union led by Count Mansfeld at the Battle of Sablat, on 10 June 1619. This cut off Count Thurn's communications with Prague, and he was forced to abandon his siege of Vienna. The Battle of Sablat also cost the Protestants an important ally — Savoy, long an opponent of Habsburg expansion. Savoy had already sent considerable sums of money to the Protestants and even troops to garrison fortresses in the Rhineland. The capture of Mansfeld's field chancery revealed the Savoyards' involvement, and they were forced to bow out of the war.

1621–1625
The Spanish sent an army from Brussels under Ambrosio Spinola to support the Emperor. In addition, the Spanish ambassador to Vienna, Don Íñigo Vélez de Oñate, persuaded Protestant Saxony to intervene against Bohemia in exchange for control over Lusatia. The Saxons invaded, and the Spanish army in the west prevented the Protestant Union's forces from assisting. Oñate conspired to transfer the electoral title from the Palatinate to the Duke of Bavaria in exchange for his support and that of the Catholic League.

The Catholic League's army (which included René Descartes in its ranks as an observer) pacified Upper Austria, while Imperial forces under Johan Tzerclaes, Count of Tilly, pacified Lower Austria. The two armies united and moved north into Bohemia. Ferdinand II decisively defeated Frederick V at the Battle of White Mountain, near Prague, on 8 November 1620. In addition to becoming Catholic, Bohemia would remain in Habsburg hands for nearly three hundred years.

This defeat led to the dissolution of the League of Evangelical Union and the loss of Frederick V's holdings. Frederick was outlawed from the Holy Roman Empire, and his territories, the Rhenish Palatinate, were given to Catholic nobles. His title of elector of the Palatinate was given to his distant cousin, Duke Maximilian of Bavaria. Frederick, now landless, made himself a prominent exile abroad and tried to curry support for his cause in Sweden, the Netherlands and Denmark.

This was a serious blow to Protestant ambitions in the region. As the rebellion collapsed, the widespread confiscation of property and suppression of the Bohemian nobility ensured the country would return to the Catholic side after more than two centuries of Hussite and other religious dissent. The Spanish, seeking to outflank the Dutch in preparation for renewal of the Eighty Years' War, took Frederick's lands, the Electorate of the Palatinate. The first phase of the war in eastern Germany ended 31 December 1621, when the Prince of Transylvania and the Emperor signed the Peace of Nikolsburg, which gave Transylvania a number of territories in Royal Hungary.

Some historians regard the period from 1621–1625 as a distinct portion of the Thirty Years' War, calling it the "Palatinate phase". With the catastrophic defeat of the Protestant army at White Mountain and the departure of the Prince of Transylvania, greater Bohemia was pacified. However, the war in the Palatinate continued: Famous mercenary leaders – such as, particularly, Count Ernst von Mansfeld – helped Frederick V to defend his countries, the Upper and the Rhine Palatinate. This phase of the war consisted of much smaller battles, mostly sieges conducted by the Spanish army. Mannheim and Heidelberg fell in 1622, and Frankenthal was taken two years later, thus leaving the Palatinate in the hands of the Spanish.

The remnants of the Protestant armies, led by Count Ernst von Mansfeld and Duke Christian of Brunswick, withdrew into Dutch service. Although their arrival in the Netherlands did help to lift the siege of Bergen-op-Zoom (October 1622), the Dutch could not provide permanent shelter for them. They were paid off and sent to occupy neighboring East Frisia. Mansfeld remained in the Dutch Republic, but Christian wandered off to "assist" his kin in the Lower Saxon Circle, attracting the attentions of Count Tilly. With the news that Mansfeld would not be supporting him, Christian's army began a steady retreat toward the safety of the Dutch border. On 6 August 1623, ten miles short of the border, Tilly's more disciplined army caught up with them. In the ensuing Battle of Stadtlohn Christian was decisively defeated, losing over four-fifths of his army, which had been some 15,000 strong. After this catastrophe, Frederick V, already in exile in The Hague, and under growing pressure from his father-in-law, James I, to end his involvement in the war, was forced to abandon any hope of launching further campaigns. The Protestant rebellion had been crushed.

Huguenot rebellions (1620–1628)
Following the Wars of Religion of 1562–1598, the Protestant Huguenots of France (mainly located in the southwestern provinces) had enjoyed two decades of internal peace under Henry IV, who, originally a Huguenot before converting to Catholicism, had protected Protestants through the Edict of Nantes. His successor, Louis XIII, under the regency of his Italian Catholic mother, Marie de' Medici, was much less tolerant. The Huguenots responded to increasing persecution by arming themselves, forming independent political and military structures, establishing diplomatic contacts with foreign powers, and finally, openly revolting against the central power. The rebellion led to major military encounters, all of which ended in defeat for the Huguenots: the Siege of Montauban in 1621, the Naval battle of Saint-Martin-de-Ré on 27 October 1622, the Capture of Ré island in 1625, and the Siege of La Rochelle in 1627–1628. The revolt became an international conflict with the involvement of England in the Anglo-French War (1627-1629). The House of Stuart in England had been involved in attempts to secure peace in Europe (through the Spanish Match), and had intervened in the war against both Spain and France. However, defeat by the French (which indirectly led to the assassination of the English leader the Duke of Buckingham), lack of funds for war, and internal conflict between Charles I and his Parliament led to cessation of English involvement in European affairs – much to the dismay of Protestant forces on the continent. France remained the largest Catholic kingdom unaligned with the Habsburg powers, and would later actively wage war against Spain. The French Crown's response to the Huguenot rebellion was not so much a representation of the typical religious polarization of the Thirty Years' War, but rather of an attempt at achieving national hegemony by an absolutist monarchy.

Danish intervention (1625–1629)
Peace following the Imperial victory at Stadtlohn was short-lived, with conflict resuming at the initiation of Denmark. Danish involvement, referred to as Low Saxon War or Kejserkrigen ("Emperor's War"), began when Christian IV of Denmark, a Lutheran who was also the Duke of Holstein, a duchy within the Holy Roman Empire, helped the Lutheran rulers of neighbouring Lower Saxony by leading an army against the Imperial forces. Denmark had feared that its sovereignty as a Protestant nation was threatened by the recent Catholic successes. Christian IV had also profited greatly from his policies in northern Germany. For instance, in 1621, Hamburg had been forced to accept Danish sovereignty. Christian IV had obtained for his kingdom a level of stability and wealth that was virtually unmatched elsewhere in Europe. This stability and wealth was paid for by tolls on the Oresund and also by extensive war reparations from Sweden. Denmark's cause was aided by France which, together with England, had agreed to help subsidize the war. Christian had himself appointed war leader of the Lower Saxon Circle and raised an army of 20,000 mercenaries and a national army 15,000 strong.

To fight him, Ferdinand II employed the military help of Albrecht von Wallenstein, a Bohemian nobleman who had made himself rich from the confiscated estates of his countrymen. Wallenstein pledged his army, which numbered between 30,000 and 100,000 soldiers, to Ferdinand II in return for the right to plunder the captured territories. Christian, who knew nothing of Wallenstein's forces when he invaded, was forced to retire before the combined forces of Wallenstein and Tilly. Christian's poor luck was with him again when all of the allies he thought he had were forced aside: England was weak and internally divided, France was in the midst of a civil war, Sweden was at war with the Polish-Lithuanian Commonwealth, and neither Brandenburg nor Saxony were interested in changes to the tenuous peace in eastern Germany. Wallenstein defeated Mansfeld's army at the Battle of Dessau Bridge (1626) and Tilly defeated the Danes at the Battle of Lutter (1626). Mansfeld died some months later of illness, apparently tuberculosis, in Dalmatia. Wallenstein's army marched north, occupying Mecklenburg, Pomerania, and Jutland itself, but was unable to take the Danish capital on the island of Zealand. Wallenstein lacked a fleet, and neither the Hanseatic ports nor the Poles would allow an Imperial fleet to be built on the Baltic coast. He then laid siege to Stralsund, the only belligerent Baltic port with sufficient facilities to build a large fleet; it soon became clear, however, that any gains from conquering the rest of Denmark would be far outweighed by the cost of continuing the war. Wallenstein feared losing his North German gains to a Danish-Swedish alliance, while Christian IV had suffered another defeat in the Battle of Wolgast; both were ready to negotiate.

Negotiations were concluded with the Treaty of Lübeck in 1629, which stated that Christian IV could keep his control over Denmark if he would abandon his support for the Protestant German states. Thus in the following two years more land was subjugated by the Catholic powers. At this point, the Catholic League persuaded Ferdinand II to take back the Lutheran holdings that were, according to the Peace of Augsburg, rightfully the possession of the Catholic Church. Enumerated in the Edict of Restitution (1629), these possessions included two Archbishoprics, sixteen bishoprics, and hundreds of monasteries. The same year, Gabriel Bethlen, the Calvinist Prince of Transylvania, died. Only the port of Stralsund continued to hold out against Wallenstein and the Emperor.

Swedish intervention (1630–1635)


Some within Ferdinand II's court did not trust Wallenstein, believing that he sought to join forces with the German Princes and thus gain influence over the Emperor. Ferdinand II dismissed Wallenstein in 1630. He was later to recall him, after the Swedes, led by King Gustaf II Adolf (Gustavus Adolphus), had successfully invaded the Holy Roman Empire and turned the tables on the Catholics.

Like Christian IV before him, Gustavus Adolphus came to aid the German Lutherans, to forestall Catholic aggression against his homeland, and to obtain economic influence in the German states around the Baltic Sea; he was also concerned about the growing power of the Holy Roman Empire, and, like Christian IV, was heavily subsidized by Cardinal Richelieu, the Chief Minister of Louis XIII of France, and by the Dutch. From 1630 to 1634, Swedish-led armies drove the Catholic forces back, regaining much of the lost Protestant territory. During his campaign he managed to conquer half of the Imperial kingdoms, making Sweden the continental leader of Protestantism until the Swedish Empire ended in 1721.

Swedish forces entered the Holy Roman Empire via the Duchy of Pomerania, which served as the Swedish bridgehead since the Treaty of Stettin (1630). After dismissing Wallenstein in 1630, Ferdinand II became dependent on the Catholic League. Gustavus Adolphus allied with France in the Treaty of Bärwalde (January 1631). France and Bavaria signed the secret Treaty of Fontainebleau (1631), but this was rendered irrelevant by Swedish attacks against Bavaria. At the Battle of Breitenfeld (1631), Gustavus Adolphus's forces defeated the Catholic League led by Tilly. A year later they met again in another Protestant victory, this time accompanied by the death of Tilly. The upper hand had now switched from the league to the union, led by Sweden. In 1630, Sweden had paid at least 2,368,022 daler for its army of 42,000 men. In 1632, it contributed only one-fifth of that (476,439 daler) towards the cost of an army more than three times as large (149,000 men). This was possible due to subsidies from France, and the recruitment of prisoners (most of them taken at the Battle of Breitenfeld) into the Swedish army. The majority of mercenaries recruited by Gustavus II Adolphus were German but Scottish mercenaries were also common. With Tilly dead, Ferdinand II returned to the aid of Wallenstein and his large army. Wallenstein marched up to the south, threatening Gustavus Adolphus's supply chain. Gustavus Adolphus knew that Wallenstein was waiting for the attack and was prepared, but found no other option. Wallenstein and Gustavus Adolphus clashed in the Battle of Lützen (1632), where the Swedes prevailed, but Gustavus Adolphus was killed.

Ferdinand II's suspicion of Wallenstein resumed in 1633, when Wallenstein attempted to arbitrate the differences between the Catholic and Protestant sides. Ferdinand II may have feared that Wallenstein would switch sides, and arranged for his arrest after removing him from command. One of Wallenstein's soldiers, Captain Devereux, killed him when he attempted to contact the Swedes in the town hall of Eger (Cheb) on 25 February 1634. The same year, the Protestant forces, lacking Gustav's leadership, were defeated at the First Battle of Nördlingen by the Spanish-Imperial forces commanded by Cardinal-Infante Ferdinand.

By the Spring of 1635, all Swedish resistance in the south of Germany had ended. After that, the Imperialist and the Protestant German sides met for negotiations, producing the Peace of Prague (1635), which entailed a delay in the enforcement of the Edict of Restitution for 40 years and allowed Protestant rulers to retain secularized bishoprics held by them in 1627. This protected the Lutheran rulers of northeastern Germany, but not those of the south and west (whose lands had been occupied by the Imperial or League armies prior to 1627).

The treaty also provided for the union of the army of the Emperor and the armies of the German states into a single army of the Holy Roman Empire (although John George I of Saxony and Maximillian I of Bavaria kept, as a practical matter, independent command of their forces, now nominally components of the "Imperial" army). Finally, German princes were forbidden from establishing alliances amongst themselves or with foreign powers, and amnesty was granted to any ruler who had taken up arms against the Emperor after the arrival of the Swedes in 1630.

This treaty failed to satisfy France, however, because of the renewed strength it granted the Habsburgs. France then entered the conflict, beginning the final period of the Thirty Years' War. Sweden did not take part in the Peace of Prague and it continued the war together with France.

Initially after the Peace of Prague, the Swedish army under Johan Banér was pushed back by the re-inforced Imperial army up north into Germany.

French intervention (1635–1648)
France, although Roman Catholic, was a rival of the Holy Roman Empire and Spain. Cardinal Richelieu, the Chief Minister of King Louis XIII of France, considered the Habsburgs too powerful, since they held a number of territories on France's eastern border, including portions of the Netherlands. Richelieu had already begun intervening indirectly in the war in January 1631, when the French diplomat Hercule de Charnacé signed the Treaty of Bärwalde with Gustavus Adolphus, by which France agreed to support the Swedes with 1,000,000 livres each year in return for a Swedish promise to maintain an army in Germany against the Habsburgs. The treaty also stipulated that Sweden would not conclude a peace with the Holy Roman Emperor without first receiving France's approval.

After the Swedish rout at Nördlingen in September 1634 and the Peace of Prague in 1635, in which the Protestant German princes sued for peace with the German emperor, Sweden's ability to continue the war alone appeared doubtful, and Richelieu made the decision to enter into direct war against the Habsburgs. France declared war on Spain in May 1635 and the Holy Roman Empire in August 1636, opening offensives against the Habsburgs in Germany and the Low Countries. France aligned her strategy with the allied Swedes in Wismar (1636) and Hamburg (1638).

After the Peace of Prague, the Swedish army under Johan Banér was pushed back into Northern Germany by the re-inforced Imperial army. The campaign took a heavy toll on the pursuers, however, and when the two armies finally met at the Battle of Wittstock in 1636 the Swedes prevailed, reversing many of the effects of their defeat at Nördlingen.

Emperor Ferdinand II died in 1637 and was succeeded by his son Ferdinand III, who was strongly inclined toward ending the war through negotiations.

French military efforts met with disaster, and the Spanish counter-attacked, invading French territory. The Imperial general Johann von Werth and Spanish commander Cardinal-Infante Ferdinand of Spain ravaged the French provinces of Champagne, Burgundy and Picardy, and even threatened Paris in 1636. Then the tide began to turn for the French. The Spanish army was repulsed by Bernhard of Saxe-Weimar. Bernhard's victory in the Battle of Compiègne pushed the Habsburg armies back towards the borders of France. Then, for a time, widespread fighting ensued until 1640, with neither side gaining an advantage.

However, the war reached a climax and the tide of the war turned clearly toward the French and against Spain in 1640 starting with the besieging and capturing of the fort at Arras. (This is the battle mentioned in Edmond Rostand's play, Cyrano de Bergerac [1897], as being the battle in which Rostand's fictional character, "Cyrano" fought.) The French conquered Arras from the Spanish following a siege that lasted from 16 June to 9 August 1640. When Arras fell, the way was opened to the French to take all of Flanders. The defeat of the Spanish at Arras and the resultant loss of Flanders, ended with the decisive defeat of the Spanish Army of Flanders in May 1643. News of these French victories provided strong encouragement to separatist movements in Spanish provinces of Catalonia and Portugal. The Catalonian revolt had sprung up spontaneously in May 1640. Since that time it had been the conscious goal of Cardinal Richelieu to promote a "war by diversion" against the Spanish. Richelieu wanted to create difficulties for the Spanish at home which might encourage them to withdraw from the war. To fight this war by diversion Cardinal Richelieu had been supplying aid to the Catalonians. In December 1640, the Portuguese rose up against Spanish rule and once again Richelieu supplied aid to the insurgents. The war by diversion had its intended effect. Philip IV of Spain was reluctantly forced to divert his attention from the war in northern Europe to deal with his problems at home. Indeed, even at this time, some of Philip's advisers, including the Count of Oñate, were recommending that Philip withdraw from overseas commitments. With both Trier, Alsace and Lorraine all in French hands and the Dutch in charge of Limburg, the Channel and the North Sea, the "Spanish Road" connecting Hapsburg Spain with the Hapsburg possessions in the Netherlands and Austria was severed. Philip IV could no longer physically send reinforcements to the Low Countries. On 4 December 1642, Cardinal Richelieu died. However, his policy of war by diversion continued to pay dividends to France. Spain was unable to resist the continuing drumbeat of French victories--Gravelines was lost to the French in 1644, followed by Hulst in 1645 and Dunkirk in 1646. To be sure the Thirty Years War would continue until the Treaty of Westphalia in 1648 and the war between France and Spain would continue for eleven more years until 1659, but in the end a new order on the continent was established. This new order was embodied in the Treaty of the Pyrenees in 1659 which finally ended the war between France and Spain.

Meanwhile, an important act in the Thirty Years War was played out by the Swedes. After the battle of Wittstock, the Swedish army regained the initiative in the German campaign. In the Second Battle of Breitenfeld in 1642, outside Leipzig, the Swedish Field Marshal Lennart Torstenson defeated an army of the Holy Roman Empire led by Archduke Leopold Wilhelm of Austria and his deputy, Prince-General Ottavio Piccolomini, Duke of Amalfi. The Imperial army suffered 20,000 casualties. In addition, the Swedish army took 5,000 prisoners and seized 46 guns, at a cost to themselves of 4,000 killed or wounded. The battle enabled Sweden to occupy Saxony and impressed on Ferdinand III the need to include Sweden, and not only France, in any peace negotiations.

In 1643, Louis XIII died, leaving his five-year-old son Louis XIV on the throne. Mere days later, French General Louis II de Bourbon, 4th Prince de Condé, Duc d'Enghien, The Great Condé defeated the Spanish army at the Battle of Rocroi in 1643. The chief minister of Louis XIII, Cardinal Mazarin, facing the domestic crisis of the Fronde in 1645, began working to end the war. In 1643, Denmark made preparations to again intervene in the war, but on the Imperial side (against Sweden). The Swedish marshal Lennart Torstenson expelled Danish prince Frederick from Bremen-Verden, gaining a stronghold south of Denmark and hindering Danish participation as mediators in the peace talks in Westphalia. Torstensson went on to occupy Jutland, and after the Royal Swedish Navy under Carl Gustaf Wrangel inflicted a decisive defeat on the Danish Navy in the battle of Fehmern Belt in an action of 13 October 1644 forcing them to sue for peace. With Denmark out of the war, Torstenson then pursued the Imperial army under Gallas from Jutland in Denmark down to Bohemia. At the Battle of Jankau near Prague, the Swedish army defeated the Imperial army under Gallas and could occupy Bohemian lands and threaten Prague as well as Vienna.

In 1645, Louis II de Bourbon, Prince de Condé defeated the Bavarian army in the Second Battle of Nördlingen. The last Catholic commander of note, Baron Franz von Mercy, died in the battle.

On 14 March 1647 Bavaria, Cologne, France and Sweden signed the Truce of Ulm. In 1648 the Swedes (commanded by Marshal Carl Gustaf Wrangel) and the French (led by Turenne and Condé) defeated the Imperial army at the Battle of Zusmarshausen and Lens. The Battle of Prague in 1648 became the last action of the Thirty Years' War. The Swedish general Hans Christoff von Königsmarck, commanding Sweden's flying column, entered the city and captured the Prague Castle (where the event that triggered the war – the Defenestration of Prague – took place, 30 years before). There they captured many valuable treasures, including Codex Gigas which is still today preserved in Stockholm, however they failed to conquer right-bank part of Prague. These results left only the Imperial territories of Austria safely in Habsburg hands.

Peace of Westphalia
Over a four-year period, the parties (Holy Roman Emperor, France and Sweden) were actively negotiating at Osnabrück and Münster in Westphalia. The end of the war was not brought about by one treaty but instead by a group of treaties such as the Treaty of Hamburg. On 15 May 1648, the Peace of Münster was signed ending the Thirty Years' War. Over five months later, on 24 October, the Treaties of Münster and Osnabrück were signed.

Casualties and disease
So great was the devastation brought about by the war that estimates put the reduction of population in the German states at about 25% to 40%. Some regions were affected much more than others. For example, Württemberg lost three-quarters of its population during the war. In the territory of Brandenburg, the losses had amounted to half, while in some areas an estimated two-thirds of the population died. The male population of the German states was reduced by almost half. The population of the Czech lands declined by a third due to war, disease, famine and the expulsion of Protestant Czechs. Much of the destruction of civilian lives and property was caused by the cruelty and greed of mercenary soldiers. Villages were especially easy prey to the marauding armies. Those that survived, like the small village of Drais near Mainz, would take almost a hundred years to recover. The Swedish armies alone may have destroyed up to 2,000 castles, 18,000 villages and 1,500 towns in Germany, one-third of all German towns.

The war caused serious dislocations to both the economies and populations of central Europe, but may have done no more than seriously exacerbate changes that had begun earlier.

Pestilence of several kinds raged among combatants and civilians in Germany and surrounding lands from 1618 to 1648. Many features of the war spread disease. These included troop movements, the influx of soldiers from foreign countries, and the shifting locations of battle fronts. In addition, the displacement of civilian populations and the overcrowding of refugees into cities led to both disease and famine. Information about numerous epidemics is generally found in local chronicles, such as parish registers and tax records, that are often incomplete and may be exaggerated. The chronicles do show that epidemic disease was not a condition exclusive to war time, but was present in many parts of Germany for several decades prior to 1618.

When the Danish and Imperial armies clashed in Saxony and Thuringia during 1625 and 1626, disease and infection in local communities increased. Local chronicles repeatedly referred to "head disease", "Hungarian disease", and a "spotted" disease identified as typhus. After the Mantuan War, between France and the Habsburgs in Italy, the northern half of the Italian peninsula was in the throes of a bubonic plague epidemic (see Italian Plague of 1629–1631). During the unsuccessful siege of Nuremberg, in 1632, civilians and soldiers in both the Swedish and Imperial armies succumbed to typhus and scurvy. Two years later, as the Imperial army pursued the defeated Swedes into southwest Germany, deaths from epidemics were high along the Rhine River. Bubonic plague continued to be a factor in the war. Beginning in 1634, Dresden, Munich, and smaller German communities such as Oberammergau recorded large numbers of plague casualties. In the last decades of the war, both typhus and dysentery had become endemic in Germany.

Witch hunts


Among the great traumas abetted by the war was a major outbreak of witchcraft persecutions that followed the first phase of the conflict. This wave of witch-hunting first erupted in the territories of the Franconian Circle, but the turmoil unleashed by the war enabled the hysteria to spread quickly to other parts of Germany. Residents of areas that had been devastated not only by the conflict itself, but also by various crop failures, famines and plagues, were quick to blame these calamities on supernatural causes and allegations of witchcraft against fellow citizens flourished. The sheer volume of trials and executions during this time would mark the period as the peak of the European witch-hunting phenomena.

The persecutions began in the Bishopric of Würzburg, which was then under the leadership of Phillip Adolf von Ehrenberg, an ardent supporter of the Counter-Reformation, who was eager to assert Catholic authority in the territories he administered. Beginning in 1626, von Ehrenberg staged numerous mass trials for witchcraft in which all levels of society, including the nobility and the clergy, found themselves targeted. By 1630 it is estimated that 219 men, women and children were burned at the stake in the city of Würzburg itself, with an additional 900 executed elsewhere in the province.

Concurrent with these events, a similar large-scale witch hunt claimed 300 to 600 lives in nearby Bamberg, where the prince-bishop erected a specially designed Malefizhaus (witch house), containing a torture chamber whose walls were adorned with Bible verses, in which to interrogate the accused. Meanwhile, in Upper Bavaria, 274 suspected witches were put to the torch in the Bishopric of Eichstatt in 1629 and another 50 perished in the adjacent district of Neuburg.

Elsewhere, the persecutions arrived in the wake of the early Imperial military successes. The witch-hunts would expand into Baden following its reconquest by Tilly, while the defeat of Protestantism in the Palatinate opened the way for their eventual spread to the Rhineland. The Rhenish electorates of Mainz and Trier would both witness mass-burnings of suspected witches during this time. In Cologne, that territory's Prince-Archbishop, Ferdinand of Bavaria, presided over a particularly brutal persecution that included the infamous trial and execution of Katharina Henot in 1627.

The witch-hunts reached their height around the time of the Edict of Restitution in 1629 and enthusiasm for them declined sharply in most areas after Sweden's entry into the war the following year. However, in Würzburg, the persecutions would continue until the death of von Ehrenberg in 1631. The excesses of this period would inspire the Jesuit scholar Friedrich Spee to author his scathing condemnation of the trials, the Cautio Criminalis. This influential work would later be credited with bringing about the end of witch-burning in some areas of Germany and its gradual abolition throughout Europe.

Political consequences
One result of the war was the division of Germany into many territories — all of which, despite their membership in the Empire, won de facto sovereignty. This limited the power of the Holy Roman Empire and decentralized German power.

The Thirty Years' War rearranged the European power structure. The last decade of the conflict saw clear signs of Spain weakening. While Spain was fighting in France, Portugal — which had been under personal union with Spain for 60 years — acclaimed John IV of Braganza as king in 1640, and the House of Braganza became the new dynasty of Portugal (see Portuguese Restoration War, for further information). Meanwhile, Spain was forced to accept the independence of the Dutch Republic in 1648, ending the Eighty Years' War. Bourbon France challenged Habsburg Spain's supremacy in the Franco-Spanish War (1635–59); gaining definitive ascendancy in the War of Devolution (1667–68), and the Franco-Dutch War (1672–78), under the leadership of Louis XIV.

From 1643–45, during the last years of the Thirty Years' War, Sweden and Denmark fought the Torstenson War. The result of that conflict and the conclusion of the great European war at the Peace of Westphalia in 1648 helped establish post-war Sweden as a force in Europe.

The edicts agreed upon during the signing of the Peace of Westphalia were instrumental in laying the foundations for what are even today considered the basic tenets of the sovereign nation-state. Aside from establishing fixed territorial boundaries for many of the countries involved in the ordeal (as well as for the newer ones created afterwards), the Peace of Westphalia changed the relationship of subjects to their rulers. In earlier times, people had tended to have overlapping political and religious loyalties. Now, it was agreed that the citizenry of a respective nation were subjected first and foremost to the laws and whims of their own respective government rather than to those of other entities, be they religious or secular.

The war also has a few more subtle consequences. The Thirty Years' War marked the last major religious war in mainland Europe, ending the large-scale religious bloodshed accompanying the Reformation, which had begun over a century before. There were other religious conflicts in the years to come, but no great wars. Also, the destruction caused by mercenary soldiers defied description (see Schwedentrunk). The war did much to end the age of mercenaries that had begun with the first Landsknechts, and ushered in the age of well-disciplined national armies.

The war also had consequences abroad, as the European powers extended their fight via naval power to overseas colonies. In 1630, a Dutch fleet of 70 ships had taken the rich sugar-exporting areas of Pernambuco (Brazil) from the Portuguese but had lost everything by 1654. Fighting also took place in Africa and Asia. The destruction of the Koneswaram temple of Trincomalee in 1624 and Ketheeswaram temple accompanied an extensive campaign of destruction of five hundred Hindu shrines, the Saraswathi Mahal Library and forced conversion to Roman Catholicism in the Tamil country conducted by the Portuguese upon their conquest of the Jaffna kingdom. The country witnessed battles of the Thirty Years' War and general hostilities of the Eighty Years' War; Phillip II and III of Portugal and later the Dutch and English used forts built from the destroyed temples, including Fort Fredrick in Trincomalee, to fight sea battles with the Dutch, Danish, the French and English which saw the beginning of the loss of the sovereign Tamil nation-state on the island.

Fiction

 * Vida y hechos de Estebanillo González, hombre de buen humor, compuesta por él mismo (Antwerp, 1646). The last of the great Spanish Golden Age picaresque novels, set against the background of the Thirty Years' War and thought to be authored by a writer in the entourage of Ottavio Piccolomini. The main character crisscrosses Europe at war in his role as messenger, witnessing, among other events, the 1634 battle of Nordlingen.
 * Simplicius Simplicissimus (1668) by Hans Jakob Christoffel von Grimmelshausen, one of the most important German novels of the 17th century, is the comic fictional autobiography of a German peasant turned mercenary who serves under various powers during the war, based on the author's first-hand experience. An opera adaptation by the same name was produced in the 1930s, written by Karl Amadeus Hartmann.
 * Daniel Defoe (1720). Memoirs of a Cavalier. "A Military Journal of the Wars in Germany, and the Wars in England. From the Years 1632 to 1648".
 * Friedrich Schiller's Wallenstein (play) trilogy (1799) is a fictional account of the downfall of this general.
 * Alessandro Manzoni's I Promessi Sposi (1842) is an historical novel taking place in Italy in 1629. It treats a couple whose marriage is interrupted, among other things, by the Bubonic Plague, and other complications of 30 Years' War.
 * Edmond Rostand's (1897) play Cyrano de Bergerac (act IV is set during the siege of Arras in 1640).
 * Alfred Döblin's sprawling historical novel Wallenstein (1920) is set in the Thirty Years' War and centers on the court of Holy Roman Emperor Ferdinand.
 * Bertolt Brecht's play Mother Courage and Her Children, an anti-war theatre piece, is set during the Thirty Years' War.
 * Queen Christina, the 1933 film starring Greta Garbo, opens with the death of Christina's father, King Gustavus Adolphus, at the Battle of Lützen in the Thirty Years' War. The subsequent plot of the film is entirely set against the backdrop of the war and her determination as Queen, as depicted a decade later, to end the war and bring about peace and resolution.
 * The Last Valley (1959) by J. B. Pick. The book upon which the film version was based. Originally published in Great Britain as The Fat Valley.
 * The Last Valley (1971). A film starring Michael Caine and Omar Sharif, who discover a temporary haven from the Thirty Years' War. Written by James Clavell, the author of Shogun.
 * Das Treffen in Telgte (1979) trans. The Meeting at Telgte (1981) by Günther Grass, set in the aftermath of the war, sets out to make implicit parallels with the postwar Germany of the late 1940s.
 * Michael Moorcock's novel, The War Hound and the World's Pain  (1981) has as its central character Ulrich von Bek, a mercenary who took part in the sack of Magdeburg.
 * Eric Flint's Ring of Fire series of novels deals with a temporally displaced American town from the early 21st century arriving in the early 1630s war torn Germany.
 * Parts of Neal Stephenson's Baroque Cycle are set in lands devastated by the Thirty Years' War.
 * Magdeburg by Heather Richardson (Belfast, Lagan Press, 2009) is a fictional account of the Sack of Magdeburg and its aftermath, and treats among other things the complexity of Lutheran and Catholic relationships and loyalties amongst both soldiers and civilians.
 * In "The Hangman's Daughter" by Oliver Pötzsch the protagonist, hangman Jakob Kuisl, and other prominent characters have served in a General Tilly's army and participated in the massacre and sacking of the city of Magdeburg during the Thirty Years War. "The Great War" and Swedish incursion into north-central Germany are frequently referenced.
 * Hermann Löns' novel Der Wehrwolf is about an alliance of peasants using guerrilla tactics to fight the enemy during the Thirty Years' War.