The Thirty Years' War was a war fought primarily in Central Europe between 1618 and 1648. One of the most destructive conflicts in human history, it resulted in eight million fatalities not only from military engagements but also from violence, famine, and plague. Casualties were overwhelmingly and disproportionately inhabitants of the Holy Roman Empire, most of the rest being battle deaths from various foreign armies.

The deadly clashes ravaged Europe; 20 percent of the total population of Germany died during the conflict and there were losses up to 50 percent in a corridor between Pomerania and the Black Forest. In terms of proportional German casualties and destruction, it was surpassed only by the period of January to May 1945 during World War II. One of its enduring results was 19th-century Pan-Germanism, when it served as an example of the dangers of a divided Germany and became a key justification for the 1871 creation of the German Empire (although the German Empire excluded the German-speaking parts of the Austro-Hungarian Empire).

Initially a war between various Protestant and Catholic states in the fragmented Holy Roman Empire, it gradually developed into a more general conflict involving most of the European great powers. These states employed relatively large mercenary armies, and the war became less about religion and more of a continuation of the France–Habsburg rivalry for European political pre-eminence and a Habsburg attempt to rebuild the imperial authority in Germany.

The war was preceded by the election of the new Habsburg Holy Roman Emperor, Ferdinand II, who tried to impose religious uniformity on his domains, forcing Roman Catholicism on its peoples. The northern Protestant states, angered by the violation of their rights to religious liberty, which had been granted in the Peace of Augsburg, banded together to form the Protestant Union. Ferdinand II was a devout Roman Catholic and much less tolerant than his predecessor, Rudolf II, who ruled from the largely Protestant city of Prague. Ferdinand's policies were considered strongly pro-Catholic and anti-Protestant.

These events caused widespread fears throughout northern and central Europe, and triggered the Protestant Bohemians living in the then relatively loose dominion of Habsburg Austria (and also within the Holy Roman Empire) to revolt against their nominal ruler, Ferdinand II. After the so-called Defenestration of Prague deposed the Emperor's representatives in Prague, the Protestant estates and Catholic Habsburgs started gathering allies for war. The Protestant Bohemians ousted the Habsburgs and elected the Calvinist Frederick V, Elector of the Rhenish Palatinate as the new king of the Kingdom of Bohemia. Frederick took the offer without the support of the Protestant Union. The southern states, mainly Roman Catholic, were angered by this. Led by Bavaria, these states formed the Catholic League to expel Frederick in support of the Emperor. The Empire soon crushed the perceived Protestant rebellion in the Battle of White Mountain, executing leading Bohemian aristocrats shortly after. Protestant rulers across Europe unanimously condemned the Emperor's action.

Contemporary painting showing the Battle of White Mountain (1620), where Imperial-Spanish forces under Johann Tserclaes, Count of Tilly won a decisive victory.

After the atrocities committed in Bohemia, Saxony finally gave its support to the Protestant Union and decided to fight back. Sweden, at the time a rising military power, soon intervened in 1630 under its king Gustavus Adolphus, transforming what had been simply the Emperor's attempt to curb the Protestant states into a full-scale war in Europe. Habsburg Spain, wishing to finally crush the Dutch rebels in the Netherlands and the Dutch Republic (which was de facto independent since 1581 but de jure still a part of the Holy Roman Empire), intervened under the pretext of helping its dynastic Habsburg ally, Austria. No longer able to tolerate the encirclement of two major Habsburg powers on its borders, Catholic France entered the coalition on the side of the Protestants in order to counter the Habsburgs.

Contemporary woodcut depicting the Old Town Square execution of Protestant aristocrats in Prague, 1621.

The Thirty Years’ War devastated entire regions, resulting in high mortality, especially among the populations of the German and Italian states, the Crown of Bohemia, and the Southern Netherlands. Both mercenaries and soldiers in fighting armies traditionally looted or extorted tribute to get operating funds, which imposed severe hardships on the inhabitants of occupied territories. The war also bankrupted most of the combatant powers.

The Dutch Republic ultimately benefited; it obtained independence from the Holy Roman Empire and also from Spain (which had directly controlled the Dutch lands despite it not being part of the Holy Roman Empire) thus concluding its 80-year revolt against Spain. It subsequently enjoyed a time of great prosperity and development, known as the Dutch Golden Age, during which it became one of the world's foremost economic, colonial, and naval powers. The Thirty Years' War ended with the Treaty of Osnabrück and the Treaties of Münster, part of the wider Peace of Westphalia. The war altered the political order of European powers. The rise of Bourbon France, the curtailing of Habsburg ambition, and the ascendancy of Sweden as a great power created a new balance of power on the continent, with France emerging from the war strengthened and increasingly dominant in the latter part of the 17th century.

Thirty Years’ War.

The Thirty Years' War.

Thirty Years’ War, (1618-48), in European history, a series of wars fought by various nations for various reasons, including religious, dynastic, territorial, and commercial rivalries. Its destructive campaigns and battles occurred over most of Europe, and, when it ended with the Treaty of Westphalia in 1648, the map of Europe had been irrevocably changed.

Although the struggles that created it erupted some years earlier, the war is conventionally held to have begun in 1618, when the future Holy Roman emperor Ferdinand II, in his role as king of Bohemia, attempted to impose Roman Catholic absolutism on his domains, and the Protestant nobles of both Bohemia and Austria rose up in rebellion. Ferdinand won after a five-year struggle.

In 1625 King Christian IV of Denmark saw an opportunity to gain valuable territory in Germany to balance his earlier loss of Baltic provinces to Sweden. Christian’s defeat and the Peace of Lübeck in 1629 finished Denmark as a European power, but Sweden’s Gustav II Adolf, having ended a four-year war with Poland, invaded Germany and won many German princes to his anti-Roman Catholic, anti-imperial cause.

Meanwhile the conflict widened, fueled by political ambitions of the various powers. Poland, having been drawn in as a Baltic power coveted by Sweden, pushed its own ambitions by attacking Russia and establishing a dictatorship in Moscow under Władysław, Poland’s future king. The Russo-Polish Peace of Polyanov in 1634 ended Poland’s claim to the tsarist throne but freed Poland to resume hostilities against its Baltic archenemy, Sweden, which was now deeply embroiled in Germany. Here, in the heartland of Europe, three denominations vied for dominance: Roman Catholicism, Lutheranism, and Calvinism. This resulted in a Gordian tangle of alliances as princes and prelates called in foreign powers to aid them. Overall, the struggle was between the Holy Roman Empire, which was Roman Catholic and Habsburg, and a network of Protestant towns and principalities that relied on the chief anti-Catholic powers of Sweden and the United Netherlands, which had at last thrown off the yoke of Spain after a struggle lasting 80 years. A parallel struggle involved the rivalry of France with the Habsburgs of the empire and with the Habsburgs of Spain, who had been attempting to construct a cordon of anti-French alliances.

The principal battlefield for all these intermittent conflicts was the towns and principalities of Germany, which suffered severely. During the Thirty Years’ War, many of the contending armies were mercenaries, many of whom could not collect their pay. This threw them on the countryside for their supplies, and thus began the “wolf-strategy” that typified this war. The armies of both sides plundered as they marched, leaving cities, towns, villages, and farms ravaged. When the contending powers finally met in the German province of Westphalia to end the bloodshed, the balance of power in Europe had been radically changed. Spain had lost not only the Netherlands but its dominant position in western Europe.

France was now the chief Western power.

Sweden had control of the Baltic.

The United Netherlands was recognized as an independent republic.

The member states of the Holy Roman Empire were granted full sovereignty. The ancient notion of a Roman Catholic empire of Europe, headed spiritually by a pope and temporally by an emperor, was permanently abandoned, and the essential structure of modern Europe as a community of sovereign states was established.

With Emperor Ferdinand II’s ascension to head of state of the Holy Roman Empire in 1619, religious conflict began to foment.

One of Ferdinand II’s first actions was to force citizens of the empire to adhere to Roman Catholicism, even though religious freedom had been granted as part of the Peace of Augsburg.

Signed in 1555 as a keystone of the Reformation, the Peace of Augsburg’s key tenet was “whose realm, his religion,” which allowed the princes of states within the realm to adopt either Lutheranism/Calvinism or Catholicism within their respective domains.

This effectively calmed simmering tensions between peoples of the two faiths within the Holy Roman Empire for more than 60 years, although there were flare ups, including the Cologne War (1583-1588) and the War of the Julich Succession (1609).

Still, the Holy Roman Empire may have controlled much of Europe at the time, though it was essentially a collection of semi-autonomous states or fiefdoms. The emperor, from the House of Habsburg, had limited authority over their governance.

But after Ferdinand’s decree on religion, the Bohemian nobility in present-day Austria and the Czech Republic rejected Ferdinand II and showed their displeasure by throwing his representatives out of a window at Prague Castle in 1618.

The so-called Defenestration of Prague (fenestration: the windows and doors in a building) was the beginning of open revolt in the Bohemian states – who had the backing of Sweden and Denmark-Norway – and the beginning of the Thirty Years’ War.

In response to Ferdinand II’s decision to take away their religious freedom, the primarily Protestant northern Bohemian states of the Holy Roman Empire sought to break away, further fragmenting an already loosely structured realm.

The first stage of the Thirty Years’ War, the so-called Bohemian Revolt, began in 1618 and marked the beginning of a truly continental conflict. Over the first decade-plus of fighting, the Bohemian nobility formed alliances with the Protestant Union states in what is now Germany, while Ferdinand II sought the support of his Catholic nephew, King Phillip IV of Spain.

Soon, armies for both sides were engaged in brutal warfare on multiple fronts, in present-day Austria and in the east in Transylvania, where Ottoman Empire soldiers fought alongside the Bohemians (in exchange for yearly dues paid to the sultan) against the Poles, who were on the side of the Habsburgs.

To the west, the Spanish army aligned with the so-called Catholic League, nation-states in present-day Germany, Belgium and France, who supported Ferdinand II.

At least initially, Ferdinand II’s forces were successful, quelling the rebellion to the east and in northern Austria, leading to the dissolution of the Protestant Union. However, fighting continued to the west, where Denmark-Norway’s King Christian IV threw his support behind the Protestant states.

Even with help from soldiers from Scotland, however, the armies of Denmark-Norway fell to the forces of Ferdinand II, ceding much of northern Europe to the emperor.

Battle of Lutzen 1632, The Yellow regiment elite gaurds with the blue regiment of Gustavus Adolf. The regiment is formed with old soldiers who have surved 7,8 years for Swedish Army. They are defending line desperately against Holy Roman Empire's imperial troops. (L)

But in 1630, Sweden, under the leadership of Gustavus Adolphus, took the side of the northern Protestants and joined the fight, with its army helping to push Catholic forces back and regain much of the lost territory lost by the Protestant Union.

With the support of the Swedes, Protestant victories continued. However, when Gustavus Adolphus was killed in the Battle of Lutzen in 1632, the Swedes lost some of their resolve.

Using military assistance of Bohemian nobleman Albrecht von Wallenstein, who provided his army of an estimated 50,000 soldiers to Ferdinand II in exchange for the freedom to plunder any captured territory, began to respond and, by 1635, the Swedes were vanquished.

The resulting treaty, the so-called Peace of Prague, protected the territories of the Lutheran/Calvinist rulers of northeastern Germany, but not those of the south and west in present-day Austria and the Czech Republic. With religious and political tensions in the latter regions remaining high, fighting continued.

The French, though Catholic, were rivals of the Habsburgs and were unhappy with the provisions of the Peace of Prague.

Thus, the French entered the conflict in 1635. However, at least initially, their armies were unable to make inroads against the forces of Ferdinand II, even after he died of old age in 1637.

Meanwhile, Spain, fighting at the behest of the emperor’s successor and son, Ferdinand III, and later under Leopold I, mounted counter-attacks and invaded French territory, threatening Paris in 1636. However, the French recovered, and fighting between the French-Protestant alliance and the forces of Spain and the Holy Roman Empire were at a stalemate for the next several years.

In 1640, the Portuguese began to revolt against their Spanish rulers, thereby weakening their military efforts on behalf of the Holy Roman Empire. Two years later, the Swedes re-entered the fray, further weakening Habsburg forces.

The next year, 1643, was pivotal in the decades-long conflict. That year, Denmark-Norway took up arms again, this time fighting on the side of the Habsburgs and the Holy Roman Empire.

At around the same time, French monarch Louis XIII died, leaving the throne to his 5-year-old son, Louis XIV, and creating a leadership vacuum in Paris.

Over the ensuing years, the French army had several notable victories, but also suffered significant defeats, particularly at the Battle of Herbsthausen in 1645. Also in 1645, the Swedes attacked Vienna, but were unable to capture the city from the Holy Roman Empire.

In 1647, the Habsburg forces led by Octavio Piccolomini were able to repel the Swedes and the French from what is now Austria.

The next year, in the Battle of Prague – the last significant fighting in the Thirty Years’ War – the Swedes captured Prague Castle from the forces of the Holy Roman Empire (and looted the priceless art collection in the castle), but were unable to take the bulk of the city.

By this time, only the Austrian territories remained under the control of the Habsburgs.

Over the course of 1648, the various parties in the conflict signed a series of treaties called the Peace of Westphalia, effectively ending the Thirty Years’ War – although not without significant geopolitical effects for Europe.

Weakened by the fighting, for example, Spain lost its grip over Portugal and the Dutch republic. The peace accords also granted increased autonomy to the former Holy Roman Empire states in German-speaking central Europe.

A frenzy of witch-hunts took place during this time in Europe, mostly in German-speaking parts, with an estimated 60,000 people put to death. In mainland Europe and Scotland they burned them, with the peak period between 1580 and 1662 often referred to as The Burning Times. England and its colonies in north America preferred hanging. (L)

Ultimately, though, historians believe the Peace of Westphalia laid the groundwork for the formation of the modern nation-state, establishing fixed boundaries for the countries involved in the fighting and effectively decreeing that residents of a state were subject to the laws of that state and not to those of any other institution, secular or religious.

This radically altered the balance of power in Europe and resulted in reduced influence over political affairs for the Catholic Church, as well as other religious groups.

As brutal as the fighting was in the Thirty Years’ War, hundreds of thousands died as a result of famine caused by the conflict as well as an epidemic of typhus, a disease that spread rapidly in areas particularly torn apart by the violence. Historians also believe the first European witch hunts began during the war, as a suspicious populace attributed the suffering throughout Europe at the time to “spiritual” causes.

The war also fostered a fear of the “other” in communities across the European continent, and caused an increased distrust among those of different ethnicities and religious faiths – sentiments that persist to some degree to this day.

The Peace of Augsburg, also called the Augsburg Settlement, was a treaty between Charles V, Holy Roman Emperor, and the Schmalkaldic League, signed in September 1555 at the imperial city of Augsburg. It officially

• ended the religious struggle between the two groups and
• made the legal division of Christianity permanent within the Holy Roman Empire,
• allowing rulers to choose either Lutheranism or Roman Catholicism as the official confession of their state.

However, the Peace of Augsburg arrangement is also credited with ending much Christian unity around Europe. Before, the main religion was Roman Catholicism with a few practicers of Lutheranism. Now, if a ruler chose for his or her subjects to practice Lutheranism, the population which endorsed and practiced Lutheranism increased greatly. Calvinism was not allowed until the Peace of Westphalia.

Peace of Augsburg, first permanent {?} legal basis for the coexistence of Lutheranism and Catholicism in Germany, promulgated on September 25, 1555, by the Diet of the Holy Roman Empire assembled earlier that year at Augsburg.

Charles V, Holy Roman emperor.

The Peace allowed the state princes to select either Lutheranism or Catholicism as the religion of their domain and permitted the free emigration of residents who dissented. The legislation officially ended conflict between the two groups, though it made no provisions for other Protestant denominations, such as Calvinism.

In 1548 the emperor Charles V established a provisional ruling on the religious strife between Lutherans and Catholics, known as the Augsburg Interim. However, by 1552 the Interim had been overthrown by the revolt of the Protestant elector Maurice of Saxony and his allies. In the ensuing negotiations at Passau (summer 1552), even the Catholic princes called for a lasting peace and feared that the religious controversy would never be settled. The emperor, however, was unwilling to recognize the religious division in Western Christendom as permanent and granted a peace only until the next imperial Diet.

Ferdinand I, engraving by Barthel Beham, 1531.

The Diet opened at Augsburg on February 5, 1555. Although the assembly was proclaimed by Charles V, he did not wish to take part in the inevitable religious compromises and refused to attend the proceedings. Instead, he empowered his brother Ferdinand (the future emperor Ferdinand I) to settle all questions. The Diet determined that no prince in the empire should make war against another on religious grounds and that this peace should remain operative until the churches were peacefully reunited. Only two churches were recognized, the Roman Catholic and the adherents of the Augsburg Confession — i.e., the Lutherans — and only one church was to be recognized in each territory. Although the religion of the prince’s choice was thus made obligatory for his subjects, those who adhered to the other church could sell their property and migrate to a territory where that denomination was recognized. The free imperial cities, which had lost their religious homogeneity a few years earlier, were exceptions to the general ruling; Lutheran and Catholic citizens in these cities remained free to exercise their religion as they pleased. The same freedom was furthermore extended to Lutheran knights and to towns and other communities that had for some time been practicing their religion in the lands of ecclesiastical princes of the empire. This last concession provoked vehement Catholic opposition, and Ferdinand circumvented the difficulty by deciding the matter on his own authority and including the clause in a separate article.

Ecclesiastical lands taken by Lutheran rulers from Catholic prelates who were not immediate vassals of the emperor were to remain with the Lutherans if continuous possession could be proved from the time of the Treaty of Passau (August 2, 1552). However, to ensure the permanence of the remaining ecclesiastical territories, the Catholics gained the condition that in the future any ecclesiastical prince who became Protestant should renounce his office, lands, and revenues. Because the Lutherans would not accept this ecclesiastical reservation and the Catholics would not yield, Ferdinand incorporated the clause on his own authority with a note that agreement had not been reached on it. In fact, Lutherans were able to nullify its effect in many cases.

The desire for a lasting settlement was so strong that the compromise peace, which satisfied no one completely and had many loopholes, was accepted. In spite of its shortcomings, the Peace of Augsburg saved the empire from serious internal conflicts for more than 50 years, and Germany thus emerged from the 16th century as a religiously divided country.

Portrait of Philip I, Landgrave of Hesse
John Frederick I of Saxony by Lucas Cranach the Younger.

The League was officially established on 27 February 1531, by Philip I, Landgrave of Hesse, and John Frederick I, Elector of Saxony, the two most powerful Protestant rulers in the Holy Roman Empire at the time. It originated as a defensive religious alliance, with the members pledging to defend each other should their territories be attacked by Charles V, the Holy Roman Emperor. At the insistence of the Elector of Saxony, membership was conditional on agreement to the Lutheran Augsburg Confession or the Reformed Tetrapolitan Confession.

Ferdinand I. Portrait by Hans Bocksberger der Ältere.

The formation of the Smalcald League in 1531 and the threatening attitude of Sultan Suleiman the Magnificent who in April 1532 assumed the offensive with an army of 300,000 men caused Ferdinand of Austria to grant this religious peace. Ferdinand had made humiliating overtures to Suleiman and as long as he hoped for a favorable response was not inclined to grant the peace which the Protestants demanded at the Diet of Regensburg which met in April 1532. But as the army of Suleiman drew nearer he yielded and on July 23, 1532 the peace was concluded at Nuremberg where the final deliberations took place. Those who had up to this time joined the Reformation obtained religious liberty until the meeting of a council and in a separate compact all proceedings in matters of religion pending before the imperial chamber court were temporarily paused.

In December, 1535, the league admitted anyone who would subscribe to the Augsburg Confession, thus Anhalt, Württemberg, Pomerania, as well as the free imperial cities of Augsburg, Frankfurt am Main, and the Free Imperial City of Kempten joined the alliance.

In 1538, the Schmalkaldic League allied with the newly reformed Denmark. In 1539, the League acquired Brandenburg, which was under the leadership of Joachim II Hector, Elector of Brandenburg. In 1545, the League gained the allegiance of the Electoral Palatinate, under the control of Frederick III, Elector Palatine. In 1544, Denmark and the Holy Roman Empire signed the Treaty of Speyer, which stated that during the reign of Christian III, Denmark would maintain a peaceful foreign policy towards the Holy Roman Empire.

The members of the League agreed to provide 10,000 infantry and 2,000 cavalry for their mutual protection. They rarely provoked Charles directly, but confiscated church land, expelled bishops and Catholic princes, and helped spread Lutheranism throughout northern Germany. Martin Luther planned to present to the League the Smalcald Articles, a stricter Protestant confession, during a meeting in 1537. Luther attended the critical meeting in 1537, but spent most of his time suffering from kidney stones. The rulers and princes even met in the home where Luther was staying. Though Luther was asked to prepare the articles of faith that came to be known as the Smalcald Articles, they were not formally adopted at the time of the meeting, though in 1580 they were included in the Book of Concord.

For fifteen years the League was able to exist without opposition, because Charles was busy fighting wars with France and the Ottoman Empire. Overall, the Ottoman-Habsburg wars lasted from 1526 until 1571.

Starting in 1535, Francis I of France, while vigorously persecuting Protestants at home, nevertheless supported the Protestant princes in their struggle against their common foe. This tactical support ended in 1544 with the signing of the Treaty of Crépy, whereby the French king, who was fighting the Emperor in Italy, pledged to stop backing the Protestant princes and the League in Germany.

In 1535 Charles led the Conquest of Tunis (1535). Francis I of France, in an effort to limit the power of the Habsburgs, allied with Suleiman the Magnificent of the Ottoman Empire, forming a Franco-Ottoman alliance. The Italian War of 1536-38 between France and the Holy Roman Empire ended in 1538 with the Truce of Nice.

The final war during this period Charles fought against France, the Italian War of 1542-46, ended with inconclusive results and the Treaty of Crépy. Following on the peace with France, the Charles signed the Truce of Adrianople in 1547 with the Ottoman Empire (which was allied with Francis). This was to free even more Habsburg resources for a final confrontation with the League.

After Charles made peace with Francis, he focused on suppressing Protestant resistance within his empire. From 1546 to 1547, in what is known as the Schmalkaldic War, Charles and his allies fought the League over the territories of Ernestine Saxony and Albertine Saxony. Although the League's military forces may have been superior, its leaders were incompetent and unable to agree on any definitive battle plans. Despite the fact that Pope Paul III withdrew his troops from the Imperial forces and halved his subsidy, on 24 April 1547, the imperial forces gathered by Charles routed the League's forces at the Battle of Mühlberg, capturing many leaders, including, most notably, Johann Frederick the Magnanimous. Philip of Hesse tried to negotiate but the Emperor refused and he surrendered in May. In theory this meant that the residents of thirty different cities were returned to Catholicism but in fact this was not the case. This battle effectively won the war for Charles; only two cities continued to resist. Many of the princes and key reformers, such as Martin Bucer, fled to England, where they directly influenced the English Reformation.

John Frederick I, Elector of Saxony, captured in the battle of Mühlberg, 24.4.1547, during the Schmalkaldic War.

In 1548 the victorious Charles forced the Schmalkaldic League to agree to the terms set forth in the Augsburg Interim. However, by the 1550s, Protestantism had established itself too firmly within Central Europe to be ended by brute force. A small Protestant victory in 1552 forced Charles to flee across the Alps to avoid capture; Ferdinand (King of the Romans,heir to the Empire) signed the Peace of Passau, which granted some freedoms to Protestants and ended all of Charles' hopes of religious unity within his empire. Three years later, the Peace of Augsburg granted Lutheranism official status within the Holy Roman Empire and let princes choose the official religion within the domains they controlled according to the principle of Cuius regio, eius religio.

Intending to strengthen the security provided by the Peace of Augsburg, Protestants formed the union in 1608. Its leaders created guidelines and agreements to live by as follows:

1. Each member shall keep in good faith with the order and their heirs, land and people, and no one shall enter into any other alliance.
2. Each member of the union should keep a secret correspondence effectively to inform each other of all dangerous and offensive affairs which may threaten each other's heirs, land and people, and to this purpose each will keep in good contact with one another.
3. Whenever important matters arise that concern the well-being of the union, the members of the union will help each other with faithful advice in order to uphold each and every one as much as possible.
4. The wish of the union in matters concerning the liberties and high jurisdictions of the German Electors and Estates should be presented and pressed at subsequent Imperial and Imperial Circle assemblies, and not merely left to secret correspondence with each other.
5. The union shall not affect our disagreement on several points of religion, but that notwithstanding these, we have agreed to support each other. No member is to allow an attack on any other in books or through the pulpit, nor give cause for any breach of the peace, while at the same time leaving untouched the theologian's rights of disputation to affirm the word of God.
6. If one of the members of the union is attacked, the remaining members of the union shall immediately come to his aid with all the resources of the union.

In 1555, the Peace of Augsburg was signed by Charles V and Lutheran princes. This treaty allowed Roman Catholic and Lutheran princes the right to decide which freedom their respective state would be under, but gave no such protection to Calvinist princes.

In 1608, Protestant princes formed the alliance known as Protestant Union.

The next year, the Catholic League was created.

In 1610, the Union intervened in the War of the Jülich Succession.

In 1618, the Thirty Years' War began with the outbreak of the Bohemian Revolt.

Frederick V, Elector Palatine, accepted the crown of Bohemia the following year.

The Union declared its neutrality in the conflict between Frederick and the Catholic League in the 1620 Treaty of Ulm.

The Union dissolved the next year.

Union, Evangelische Union, or Union von Auhausen, military alliance (1608-21) among the Protestant states of Germany for mutual protection against the growing power of the Roman Catholic states of Counter-Reformation Europe.

In February 1608, at the Diet (Reichstag) of the Holy Roman Empire, the Catholic princes introduced a motion calling for the restitution of all recently secularized church lands. When it was rejected, a group of Protestant princes submitted a formal protest and walked out of the Diet. Six of them—the elector Palatine of the Rhine, the dukes of Neuburg and Württemberg, and the margraves of Baden-Durlach, Ansbach, and Kulmbach—then gathered in the secularized monastery at Auhausen, near Nördlingen in southern Germany, and on May 14 they formed a defensive union for 10 years, pledging mutual support in case of attack. Although the elector Palatine served as “director” of the union, its leading spirit was the chairman of its military council, Prince Christian of Anhalt-Bernburg, and he immediately sought to expand the alliance. Before long, nine princes and 17 towns joined, while England, the Dutch Republic, and Sweden all promised support. These developments provoked the counteralliance of the Catholic League (1609) under Duke Maximilian I of Bavaria.

From the outset, internal strife between the union’s Lutheran and Calvinist members and between the cities and the territorial magnates undermined its strength. The powerful Protestant elector of Saxony refused to join, and by 1617, when the union came up for renewal, several members had defected (notably the elector of Brandenburg). Although the remaining members agreed to renew their pact for another four years, they stipulated that the union would mobilize only to defend the existing territories of a member. The importance of this qualification emerged in 1619 when the Bohemian estates offered their crown to Elector Frederick V of the Upper Palatinate, the union’s director: its members made clear that they would defend only his German territories. The following year they even complained that he was spending too long in Bohemia and threatened to withhold his salary as director. Admittedly, when the Catholic League mobilized, the Protestant Union also raised troops; but soon afterward it agreed to a neutrality pact (the Treaty of Ulm, July 3, 1620) by which both sides agreed not to attack each other. This freed the Catholic League’s army to invade Bohemia, leading to the defeat of Frederick and Anhalt at the Battle of White Mountain. With the Catholics triumphant and with Frederick and Anhalt in exile, the Protestant Union dissolved itself on April 12, 1621.

b/w print showing walled city ablaze in the background; many armed men approach from left; cannons are firing from left foreground; text box in bottom center.

The Sack of Magdeburg, also called Magdeburg's Wedding (German: Magdeburger Hochzeit) or Magdeburg's Sacrifice (German: Magdeburgs Opfergang), was the destruction of the Protestant city of Magdeburg on 20 May 1631 by the Imperial Army and the forces of the Catholic League, resulting in the deaths of around 20,000, including both defenders and non-combatants.

The event is considered the worst massacre of the Thirty Years’ War.

Magdeburg, then one of the largest cities in Germany, having well over 25,000 inhabitants in 1630, did not recover its importance until well into the 18th century.

Archbishopric of Magdeburg

The archbishopric of Magdeburg was established as an ecclesiastical principality in 968. In political respect the Erzstift, the archiepiscopal and capitular temporalities, had gained imperial immediacy as prince-archbishopric in 1180. This meant that the archbishop of Magdeburg ruled the town and the lands around it in all matters, worldly and spiritual.

Protestant Reformation

The citizens of Magdeburg had turned Protestant in 1524 and joined the Schmalkaldic League against the religious policies of the Catholic emperor Charles V in 1531. During the Schmalkaldic War of 1546/47, the Lower Saxon city became a refuge for Protestant scholars, which earned it the epithet Herrgotts Kanzlei (German for 'Lord's Chancellery'), but also an Imperial ban that lasted until 1562. The citizens refused to acknowledge Emperor Charles's Augsburg Interim and were besieged by Imperial troops under Maurice, Elector of Saxony in 1550/51.

Protestant archbishops and Administrators

The Roman Catholic archdiocese had de facto turned void since 1557, when the last papally confirmed prince-archbishop, the Lutheran Sigismund of Brandenburg came of age and ascended to the see.

Openly Lutheran Christian William of Brandenburg, elected to be archbishop in 1598, was denied recognition by the imperial authorities. Since about 1600, he styled himself Administrator of Magdeburg, as did other Protestant German notables assigned to govern principalities that were de jure property of the Catholic church.

Alliance with the Danish king

During the Thirty Years' War, Administrator Christian William entered into an alliance with Denmark. In 1626, he led an army from Lower Saxony into the Battle of Dessau Bridge. After Wallenstein won this battle, Christian William fled abroad. In 1629, he fled to the court of King Gustavus Adolphus of Sweden.

As a result of these developments, in January 1628, the Magdeburg cathedral chapter deposed Christian William and elected August of Wettin, 13-year-old son of John George I, Elector of Saxony, as Administrator. This meant little for the moment, however, as Augustus could not assume office due to his father's continued unwillingness to provoke the emperor.

Edict of Restitution

In March 1629, emperor Ferdinand II passed the Edict of Restitution. It was specifically aimed at restoring the situation of the 1555 Peace of Augsburg in ecclesiastical territories that had since strayed from "legal" Catholic faith and rule. Bremen and Magdeburg were the biggest examples of territories to be restituted.

Alliance with the Swedish king

The city's councillors had been emboldened by King Gustavus Adolphus's landing in Pomerania on 6 July 1630;[2] the Swedish king was a Lutheran Christian, and many of Magdeburg's residents were convinced that he would aid them in their struggle against the Roman Catholic Habsburg emperor, Ferdinand II. However, not all Protestant princes of the Holy Roman Empire had immediately embraced Adolphus;[3] some believed his chief motive for entering the war was to take northern German ports, which would allow him to control commerce in the Baltic Sea.

In November 1630, King Gustavus sent ex-Administrator Christian William back to Magdeburg, along with Dietrich von Falkenberg to direct the city's military affairs. Backed by the Lutheran clergy, Falkenberg had the suburbs fortified and additional troops recruited.

Siege of Magdeburg by Tilly in 1631.
Soldiers during the siege of Magdeburg.

Magdeburg besieged

When the Magdeburg citizens refused to pay a demanded tribute to the emperor, Imperial forces under the command of Johann Tserclaes, Count of Tilly laid siege to the city within a matter of months. The city was besieged from 20 March 1631 and Tilly put his subordinate Imperial Field Marshal Gottfried Heinrich Graf zu Pappenheim, a Catholic convert, in command while he campaigned elsewhere. During fierce fighting, Imperial troops numbering 24,000, roughly the same number as Magdeburg's entire population, conquered several sconces of the city's fortification and Tilly demanded capitulation.

General Tilly (1559-1632).

After two months of siege and despite the Swedish victory in the Battle of Frankfurt an der Oder on 13 April 1631, Pappenheim finally convinced Tilly, who had brought reinforcements, to storm the city on 20 May with 40,000 men under the personal command of Pappenheim. The Magdeburg citizens had hoped in vain for a Swedish relief attack. On the last day of the siege, the councillors decided it was time to sue for peace, but word of their decision did not reach Tilly in time.

In the early morning of 20 May, the attack began with heavy artillery fire. Soon afterward, Pappenheim and Tilly launched infantry attacks. The fortifications were breached; Imperial forces were able to overpower the defenders and open the Kröcken Gate, which allowed the entire army to enter the city and plunder its rich stores of goods. The city's defense was dealt another blow when commander Dietrich von Falkenberg was shot dead by Catholic Imperial troops.

Magdeburg burns down

There are reports of the attackers setting fire to single houses to dislodge persistent defenders. That the fire then spread all over the city appears to have been unintended. By ten o'clock most of the city was on fire. General Tilly sent some soldiers to save the cathedral, where 1,000 survivors had fled. Most of the victims in the sack suffocated or burned to death. The wind fanned the flames, in the end destroying 1,700 of the city's 1,900 buildings.

Out of control

Amidst this inferno, many Imperial soldiers supposedly went out of control. The invading soldiers had not received payment for their service and demanded valuables from every household they encountered. There were reports of gang rapes of minors and torture.

Of the 25,000 inhabitants, only 5,000 survived, at least 1,000 of these having fled into Magdeburg Cathedral and 600 into the Premonstratensian monastery. Tilly finally ordered an end to the looting on 24 May, and a Catholic mass was celebrated at the Cathedral on the next day. For another fourteen days, charred bodies were dumped in the Elbe River to prevent disease.

A census conducted in 1632 listed only 449 inhabitants. Much of the city remained rubble until at least 1720.

Reactions

After Magdeburg's capitulation to the Imperial forces, there were disputes between those residents who had favored resistance to the emperor and those who had opposed it. Even King Gustavus Adolphus joined, claiming the citizens of Magdeburg had not been willing to pay the necessary funds for their defense.

A portrait of Pope Urban VIII, by Pietro da Cortona (1627) Pope Urban VIII (Urbanus VIII; baptised 5 April 1568 – 29 July 1644) was head of the Catholic Church and ruler of the Papal States from 6 August 1623 to his death in 1644. He expanded the papal territory by force of arms and advantageous politicking, and was also a prominent patron of the arts and a reformer of Church missions. (W)

Pope Urban VIII wrote a congratulatory letter to Tilly on 18 June, saying: “You have washed your victorious hands in the blood of sinners.” (Original Latin quote: "Potuisti lavare victrices manus in sanguine peccatorum." This paraphrases Psalm 58. 10 (KJV) (Psalm 57 in the Latin Vulgate).)

The Imperial treatment of defeated Magdeburg helped persuade many Protestant rulers in the Holy Roman Empire to stand against the Roman Catholic emperor.

Notoriety

The devastations were so great that Magdeburgisieren (or "magdeburgization") became a common term signifying total destruction, rape and pillaging for decades. The terms "Magdeburg justice", "Magdeburg mercy" and "Magdeburg quarter" also arose as a result of the sack, used originally by Protestants when executing Roman Catholics who begged for quarter.

The massacre was forcefully described by Friedrich Schiller in his 1792 work History of the Thirty Years' War and perpetuated in a poem by Goethe. A scene of Brecht's play Mother Courage and Her Children, written in 1939, also refers to the event.

Political consequences

Administrator Christian William of Brandenburg was badly injured and taken prisoner. He later converted to Catholicism and was released. He received an annual sum of 12000 taler from the revenues of the archbishopric of Magdeburg under the Peace of Prague.

After the sack the archbishopric of Magdeburg went to Archduke Leopold Wilhelm of Austria, youngest son of emperor Ferdinand II, as the new Catholic Administrator. The Peace of Prague (1635) confirmed his rule over the city, but three years later, Swedish troops expelled the Habsburg army and restored Augustus of Wettin, (first elected in 1628) as Administrator as of October 1638. August finally took full control of Magdeburg in December 1642 after a neutrality treaty was concluded with the Swedish general Lennart Torstenson. He was then able to begin the reconstruction of the city.

The Archbishopric of Magdeburg was secularized and finally fell to Brandenburg-Prussia, upon August's death in 1680.

The Catholic League (Latin: Liga Catholica, German: Katholische Liga) was a coalition of Catholic states of the Holy Roman Empire formed 10 July 1609. While initially formed as a confederation to act politically to negotiate issues vis-à-vis the Protestant Union (formed 1608), modelled on the more intransigent ultra-Catholic French Catholic League (1576), it was subsequently concluded as a military alliance “for the defence of the Catholic religion and peace within the Empire.”

Notwithstanding the league's founding, as had the founding of the Protestant Union, it further exacerbated long standing tensions between the Protestant reformers and the adherents of the Catholic Church which thereafter began to get worse with ever more frequent episodes of civil disobedience, repression, and retaliation that would eventually ignite into the first phase of the Thirty Years' War roughly a decade later with the act of rebellion and calculated insult known as the Second Defenestration of Prague on 23 May 1618.

Peace of Augsburg

In 1555, the Peace of Augsburg was signed, which confirmed the result of the Diet of Speyer (1526) and ended the violence between the Catholics and the Lutherans in the Holy Roman Empire.

It stated that:

• Princes of the Holy Roman Empire (numbering 225) could choose the religion (Catholicism or Lutheranism) for their realms according to their conscience (the principle of cuius regio, eius religio).
• Lutherans living in an ecclesiastical state (under the control of a Catholic prince-bishop) could remain Lutherans.
• Lutherans could keep the territory that they had captured from the Catholic Church since the Peace of Passau (1552).
• The ecclesiastical leaders of the Catholic Church (bishops) that converted to Lutheranism had to give up their territory (the principle called reservatum ecclesiasticum).

Those occupying a state that had officially chosen either Catholicism or Lutheranism could not practice the religion differing to that of the state.

Although the Peace created a temporary end to hostilities, the underlying bases of the religious conflict remained unsolved. Both parties interpreted it at their convenience, the Lutherans in particular considering it only a momentary agreement. Further, Calvinism spread quickly throughout the Holy Roman Empire, adding a third major Christian worldview to the region, but its position was not supported in any way by the Augsburg terms, since Catholicism and Lutheranism were the only permitted creeds.

Motivations for a Catholic alliance

Donauwörth processions

German: Kreuz- und Fahnengefecht (de), lit. 'Cross and Flag engagement'

The best documented reason of the foundation of the Catholic League was an incident in the town of Donauwörth, a Free Imperial City within the territory of Bavaria. On 25 April 1606, the Lutheran majority of the town barred the Catholic residents of the town from holding an annual Markus procession, to show the rule of their confession over the town. The Catholics, led by five monks, wanted to pass through the town and on to the nearby village of Ausesheim, showing their flags and singing hymns. They were permitted to do so by the terms of the Peace of Augsburg. The city council would only allow them to re-enter town without flags and singing. The conflict ended in a brawl.

On protest of the bishop of Augsburg, Catholic Emperor Rudolf II of Habsburg threatened an Imperial ban in case of further violation of the rights of the Catholic citizens. Nevertheless, next year similar anti-Catholic incidents of civil disobedience took place, and the participants of the Markus procession were thrown out of town.

Emperor Rudolf then declared an Imperial ban on the town and ordered Maximilian I, Duke of Bavaria to execute the ban. Facing his army, the town surrendered. According to Imperial law, the disciplinary measures should not have been executed by the Catholic duke of Bavaria, but by the Protestant duke of Württemberg, who, like Donauwörth, was a member of the Swabian Imperial Circle. Maximilian de facto absorbed the former Free Imperial City, which was a violation of Imperial law as well.

Protestant Union formed

In the same year, 1607, the Catholic majority of the Reichstag meeting in the Diet of Augsburg resolved that the renewal of the Peace of Augsburg of 1555 should be conditional on the restoration of all church land appropriated since 1552. Acting on these events, the Protestant princes formed a military alliance on 14 May 1608, the Protestant Union, whose leader was Frederick IV of Wittelsbach, the Elector Palatine.

To create a union of Catholic states as a counterpart to this Protestant Union, early in 1608 Maximilian started negotiations with other Catholic princes. On 5 July 1608, the spiritual electors manifested a tendency in favour of the confederacy suggested by Maximilian. Opinions were even expressed as to the size of the confederate military forces to be raised.

Munich Diet

In July 1609, the representatives of the Prince-Bishops of Augsburg, Constance, Passau, Regensburg, and Würzburg assembled at Munich. The Prince-Archbishop of Salzburg, having shown disapproval, was not invited, and the Prince-Bishop of Eichstädt hesitated. On 10 July 1609, the participating states concluded an alliance "for the defence of the Catholic religion and peace within the Empire." The most important regulation of the League was the prohibition of attacks on one another. Instead of fighting, conflicts had to be decided by the laws of the Empire or, if these failed to solve the conflict, by arbitration within the League. Should one member be attacked, it had to be helped with military or alternatively legal support. Duke Maximilian was to be the president, and the Prince-Bishops of Augsburg, Passau, and Würzburg his councillors. The League was to continue for nine years.

The Munich Diet failed to erect a substantial structure for the newly formed League. On 18 June 1609, the Electors of Mainz, Cologne, and Trier had proposed an army of 20,000 men. They had also considered making Maximilian president of the alliance, and on August 30 they announced their adhesion to the Munich agreement, provided that Maximilian accepted the Elector of Mainz, arch-chancellor of the Empire, as co-president.

Meeting at Würzburg

To create a structure, several general meetings of the members were arranged. On 10 February 1610, the representatives of all the important Catholic states, except for Austria and Salzburg — and a great number of the smaller ones — met at Würzburg to decide the organization, funding and arming of the League. This was the real beginning of the Catholic League. The Pope, the Emperor and the King of Spain, who had been informed by Maximilian, were all favorably disposed towards the undertaking.

The main problem of the League was the unreadiness of its members. In April 1610, the contributions of all its members were not yet paid; Maximilian threatened to resign. To prevent him from doing so, Spain, which had made the giving of a subsidy dependent on Austria's enrollment in the League, waived this condition, and the pope promised a further contribution.

War of the Jülich Succession

The conduct of the Union in the Jülich dispute and the warlike operations of the Union army in Alsace seemed to make a battle between League and Union inevitable.

House Habsburg joins

In the year 1613 at Regensburg, the Austrian Habsburgs joined the League. The assembly now appointed no less than three war-directors: Duke Maximilian, and Archdukes Albert and Maximilian of Austria. The object of the League was now declared "a Christian legal defense".

The membership of the Habsburg monarchy made the League part of the struggles between the emperor and his Protestant vassals in Bohemia and Lower Austria, that would lead to the beginning of the Thirty Years' War. The first half of the war would see the emperor using the Catholic League forces as the most important part of his Imperial army.

Bavaria leaves in protest

Duke Maximilian refused to accept the resolutions of Ratisbon and even resigned the post as president, when Archduke Maximilian III of Austria, the Prince Elector of Mainz and the Prince Elector of Trier, protested the inclusion of the Bishop of Augsburg, and the Provost of Ellwangen in the Bavarian Directory. On 27 May 1617, with the Prince-Bishops of Bamberg, Eichstädt, Würzburg, and the Prince-Provost of Ellwangen, Bavaria formed a separate league for nine years.

Bohemian revolt

Already having been crowned King of Bohemia in 1617, Ferdinand II and his Catholic governors were deposed by rebelling Protestant Czech nobles in the second defenestration of Prague in 1618. The Bohemian estates went on to elect Frederick V, Elector Palatine as their king, on August 26 and 27, 1619. After his election as German Emperor on August 28, Ferdinand conferred with the spiritual electors at Frankfurt, asking for the support of the League.

Catholic League reestablished

At the end of 1618, the position of the Emperor in Bohemia as in Lower and Upper Austria gradually became critical. Searching for help, the Emperor tried to restore the League. A meeting of several of the ecclesiastical Princes decided to reconstruct the League on its original basis. It would consist of two groups: the Rhenish district under the presidency of Mainz, and the Oberland district, presided by Bavaria; the treasury and the military command were to be considered separate. Maximilian could only lead the whole of the troops when he had to appear in the Rhenish district. On 31 May, the Oberland both groups were established and bound themselves to render mutual help for six years.

Treaty of Munich

The Treaty of Munich was signed on October 8, 1619 between Emperor Ferdinand II and Duke Maximilian of Bavaria. A Spanish ambassador named Oñate persuaded Ferdinand to grant Maximilian any part of the Electoral Palatinate to occupy, as well as the electoral seat of Frederick V. Moreover, Oñate exceeded his duties by guaranteeing Ferdinand Spanish support in dealing with the Bohemian rebels. Based on the terms of the treaty, Maximilian, leader of the Catholic League, made his Bavarian forces available to Emperor Ferdinand.

Now the formation of a confederate army began. With 7,000 men, Bavaria supplied the largest contribution to the army, whose strength was fixed at Würzburg in December 1619, as 21,000 infantry and 4000 cavalry. Commander in chief was Johann Tserclaes, Count of Tilly, a descendant of a Catholic Brabantine family.

Decline and end of the Protestant Union

Facing the superiority of the League army of 30,000 men confronting the Protestant Union's army of 10,000, on 3 July 1620, the Union agreed to cease all hostilities between both parties during the war in Austria and Bohemia in the Treaty of Ulm and dissolved the following year.

Bohemian campaign

Without the risk of an attack the League could use all its military forces to support the emperor. The same month, the army was relocated to Upper Austria. Tilly won the Battle of White Mountain north of Prague on 8 November 1620, in which half of the enemy forces were killed or captured, losing only 700 men. The Emperor regained control over Bohemia and the first stage of the League's activity during the Thirty Years' War ended.

Palatinate campaigns

1622 campaign

In the spring of 1622 General Tilly moved the League's army to invade the Electoral Palatinate. They were defeated by General Mansfeld's troops at the Battle of Mingolsheim on 27 April 1622. Retreating eastwards they were joined by a Spanish army under General Córdoba. When another Protestant army under Georg Friedrich, Margrave of Baden attacked on May 6, Tilly's League force convincingly won the Battle of Wimpfen, scattering the enemy. The Battle of Höchst on June 20 proved to be the decisive victory for 1622.

After that battle the Protestant forces still fighting for Frederick V of the Palatinate withdrew over the Rhine and allowed the Catholic League army freedom of action. Consequently, Tilly captured the city of Heidelberg, Frederick's main city, following an eleven-week siege on September 19. Mannheim followed on November 2, after a ten day siege.

This could have meant the end of the war. With the exception of the still besieged fortress of Frankenthal, the Electoral Palatinate was occupied by League forces while Count Frederick was in Dutch exile.

Stadtlohn campaign

Alas, in 1623, Frederick had Christian of Brunswick, raise another army to continue the fight. However, Christian found little success and no allies on his short campaign. When Tilly approached with the League army, the Protestants made for the Dutch border. Tilly cut them off five miles short of it in the Battle of Stadtlohn on August 6, destroying another Protestant army.

This victory marks the end of the Bohemian-Palatinate phase of the war. Armed opposition against the Emperor and his anti-Protestant policies had ceased.

Danish War

This caused Denmark's king Christian IV to enter the Thirty Years' War in 1625 to protect Protestantism and also in a bid to make himself the primary leader of Northern Europe.

The league's army fought and defeated the Danish on 26–27 August 1626 at the Battle of Lutter, destroying more than half the fleeing Danish army. Because this and other victories by Wallenstein, Denmark was forced to sue for peace at the Treaty of Lübeck.

Edict of Restitution

Supported by the Catholic princes and their victorious League army, the emperor now moved to denounce Protestantism as illegal in many territories of Northern Germany.

In March 1629, emperor Ferdinand II passed the Edict of Restitution. It was specifically aimed at restoring the situation of the 1555 Peace of Augsburg in ecclesiastical territories that had strayed from "legal" Catholic faith and rule, in the decades since then.

Bremen and Magdeburg were the biggest examples of territories to be restituted. Afraid that the Catholic League's army would be sent to enforce this new law, if challenged, their protestant authorities again looked abroad for allies to protect them.

Swedish War

Sack of Magdeburg

While the Swedish King Gustavus Adolphus landed his army in Pomerania and tried to make alliances with the leaders of Northern Germany, the League's army laid siege to the city of Magdeburg for two months from 20 March 1631, as the city had promised to support Sweden. On May 20, 40,000 successfully attacked Magdeburg. A massacre of the populace ensued in which 25,000 of the 30,000 inhabitants of the city perished while fires destroyed much of the city.

The Catholic League in defeat

In 1630, Ferdinand II dismissed his Generalissimus Wallenstein. Now, the Catholic League was in control of all the Catholic armed forces.

At the First Battle of Breitenfeld, the Catholic League led by General Tilly was defeated by the Swedish forces. A year later (1632), they met again in the Battle of Rain, and this time General Tilly was killed. The upper hand had now switched from the league to Sweden and her allies, who were able to attack and capture or destroy the territories of the Catholic League. Even Munich, the capital of the most powerful member state, Electoral Bavaria, was conquered.

Thereafter, the German Catholic League did not play a major role in later events.

The Peace of Prague of 30 May 1635, was a treaty between the Holy Roman Emperor, Ferdinand II, and most of the Protestant states of the Empire. It effectively ended the civil war aspect of the Thirty Years' War. The Edict of Restitution of 1629, was effectively revoked, with the terms of the Peace of Augsburg of 1555 being reestablished.

One of the most important regulations was that formal alliances between states of the Empire were prohibited. The armies of the various states were to be unified with those of the Emperor as an army for the Empire as a whole. The result of this clause was the end of the Catholic League, a now prohibited alliance between states of the Empire.

As well as ending the fighting between the various states, the treaty also ended religion as a source of national conflict; the principle of cuius regio, eius religio was established for good within the Empire.