How did the Peace of Augsburg (1555) lead to the Thirty Years War (1618-1648)?

Emperor Charles V at the Battle of Mulhberg

The Peace of Augsburg (1555) was a peace treaty that sought to end the religious struggle in the German lands and the Holy Roman Empire in the mid-sixteenth century. The Peace of Augsburg was signed by Charles V, the Holy Roman Emperor, who was a Catholic and the Protestant Schmalkaldic League. The treaty of Augsburg was an attempt to end the series of religious wars that had destabilized the Holy Roman Empire, which was the largest political entity in Europe at the time.

The treaty, also known a the Settlement of Augsburg, sought to prevent Catholics and Protestants from going to war again and to end religious tensions and violence in the Imperial lands. The treaty briefly did maintain peace in the Holy Roman Empire, but the treaty ultimately failed. Why did the Peace of Augsburg fail, and how did it lead to the Thirty Years Wars?

The settlement ultimately failed because it did not admit Calvinist to the terms of the treaty, and it was unable to define the religious status of the Episcopal states. Most importantly, it created a mutually hostile Protestant and a Catholic bloc in Central Europe. This hostility eventually led to the Thirty Years War, the most brutal conflict, according to some, in European history.

What conflict did the Peace of Augsburg end?

Portrait of Martin Luther

The Holy Roman Empire was a fragmented collection of largely independent states of various sizes. The Holy Roman Emperor, a member of the House of Hapsburg, directly ruled some of the lands, but he was only a ‘nominal head of state in the rest of the Empire.’[1] The Hapsburg’s hereditary rulers of Austria, were elected Emperor by the major states in the Empire.

As a result, it was a very loose federation. It has often been likened to the modern European Union. In 1517, Martin Luther nailed his 95 theses on the door of the Cathedral in Wittenberg. In these, he challenged the Pope's authority and called for the reform of the Church based on the Bible. Luther's actions initiated the Reformation in the Holy Roman Empire.

The Catholic Church attempted to suppress Luther, and he was forced to seek the protection of the ruler of Saxony. The message of Luther and his calls to reform the church was greeted enthusiastically in many parts of Germany. The elite and the urban middle class were tired of the corruption and worldliness of the Church. This led to the establishment of many break-away churches that refused to acknowledge the authority of the Pope. Many temporal rulers in Germany adopted Protestantism and secularized Church lands and established Protestant Churches in their land.

In 1531, these Protestant rulers came together to form the Schmalkaldic League, a military and a political alliance, and ‘promote and expand Protestantism.’[2] Charles V was the Holy Roman Emperor and a Catholic, and he lost control of much of Germany to the League. He tried to enter negotiations with the Protestant League, but these were unsuccessful.

The supporters of Luther knew that Charles was too preoccupied with his wars in Italy and the Ottoman’s to intervene. Only after Charles V had defeated the French king could he turn his attention to Germany affairs. He formed a League that aimed to destroy Protestantism and re-establish religious unity in the Empire. Charles and his army were victorious and captured Saxony, and won a great victory at the Battle of Milberg.

Despite these defeats, the Protestants refused to come to terms and abandon their faith. Charles became aware that it would be impossible to destroy Protestantism. One of his League members defected to the Protestants, and he helped them win a minor victory. This shift convinced the aged and infirm Charles of the futility of any further war.

By the 1550s, Protestantism had been established too firmly within the Empire Central Europe to be ended by arms. Charles V wanted to secure his son's succession to Spain's throne and his nephew to the crown of the Holy Roman Emperor, and this required peace. He decided to ‘come to terms with the Protestants, which led ‘first to an armistice and then to the Treaty of Augsburg.’ [3]

How do you Define the Peace of Augsburg?

The Peace of Augsburg, also called the Augsburg Settlement, was signed in September 1555 by Charles V, Holy Roman Emperor, and the Schmalkaldic League signed on 25 September 1555 at the imperial city Augsburg.[4] It officially ended the religious war. It attempted to establish a religious settlement in the sprawling German lands.[5] The principle of cuius regio, eius religio, was the most important aspect of the treaty. This principle states that the ruler of the realm decided the faith of the people.[6] This was to ensure the states' internal unity within the Holy Roman Empire. If a ruler was Catholic, he could determine that all those who lived in his realm had to be Catholics. Those who did not accept the situation could migrate to a jurisdiction that was Protestant.

A Lutheran ruler had the same rights about the religion of his subjects as a Catholic. There were the many Ecclesiastical States in the Holy Roman Empire, such as Cologne's city-state.[7]. These were realms that were ruled by Catholic Bishops or Archbishops. If a prelate changed his faith to Protestantism, he was expected to resign and make way for another Catholic bishop.[8] Knights were also exempted from the requirement of religious uniformity, and they could still practice their faith even if it were at odds with that of their ruler. One of the most critical aspects of the Treaty was that it only applied to Lutherans and Catholics. Rulers who followed Calvinism and the teachings of the Anabaptists were not recognized.

The rights of members of these churches were also not recognized by the Peace, and they not accorded parity of esteem with Catholics and Protestants. The treaty sought to ensure a balance of power between Germanys’ Protestants and Catholics and ensure peace and end sectarian strife. It managed to end the war in the near term, but the religious conflict persisted in some parts of Germany. The Peace of Augsburg guaranteed that the House of Hapsburg would continue to be elected the Imperial ruler. However, the Emperor had little or no control of northern Germany, the heartland of Lutheranism.

Did the Peace of Augsburg end religious tensions?

Defenestration of Prague 1618

The Peace of Augsburg created a temporary end to hostilities; it did not resolve the underlying religious tension in Germany and central Europe. There were continued tensions between Catholics and Protestants. Despite the agreement that those who did not share the religion of the prince or ruler should conform or leave the realm, in the treaty, many did not. This meant that there were rival groups of Catholics and Protestants living near each other in an uneasy peace. There are many instances of riots and violence between the two groups.

The situation was made more complex by the spread of Calvinism in the latter part of the sixteenth century. Many Germans were drawn to Calvin's teachings and his ideas on the ‘elect’ and ‘predestination.’ Several German rulers, especially in Brandenburg and the Rhineland, tolerated Calvinists. The Calvinists, although Protestants were not Lutherans and they were distrusted and even persecuted by Lutheran rulers.

Catholics naturally saw them as just another Protestant sect. The Peace of Augsburg did not foresee the rise of Calvinism in Germany. At the time of the writing of the treaty, they were a small group. By the 1580s, they were a significant minority, and their activities helped increase Germany's religious tensions. By the 1600s, several rulers proclaimed themselves Calvinists, such as the Landgrave of Hesse-Kassel and the Elector of Brandenburg. As Calvinists, they were not covered by the principle of ‘one ruler, one faith.’ This threw the entire Peace of Augsburg into doubt.

Furthermore, Calvinists, because they were recognized under the Peace of Augsburg, were in effect unable to secure any tolerance for their faith in the Empire. This was to play an important part in the breakdown of the Augsburg Settlement. Indeed, the collapse of the Augsburg settlement can be attributed to actions borne out of Calvinists' frustrations. The so-called ‘defenestration of Prague’ involved Calvinists attacking and throwing the Holy Roman Emperor's representatives out a window. This was to trigger the Thirty Years War that left most of central Europe a wasteland.[9]

What was the source of the continuing tension between Catholics and Protestants?

In the Holy Roman Empire, there were very many ecclesiastical principalities. They ranged in size from a small town to large territories, often containing significant urban centers such as Cologne. The Treaty, after protracted negotiations, had to deal with the issue of ecclesiastics who converted to Lutheranism. The Catholic side was concerned that a bishop or another religious leader converted that his realm would become Lutheran. This had happened during the Reformation. The Head of the Teutonic Knights in Prussia, originally an order of warrior-monks, had converted to Protestantism, and as a result, all the Prussian territories had become Protestant. The Catholics demanded that any bishop or religious leader that had converted to Lutheranism should return his realm as by rights their lands belonged to the Catholic Church.

However, those bishops and others who had converted refused to return their lands and became the secular ruler of the former ecclesiastical principalities. This was a source of continuing tension between the Protestants and the Catholics. Many of the latter believed that the Protestant side had not respected or fully implemented Augsburg's treaty. This led to frequent clashes between both members of both confessions over the future of Episcopal principalities. For example, in the Cologne War (1583-1588), when the prince-archbishop became a Protestant, it led to a brutal sectarian war between Catholics and Lutherans. One of the Thirty Years War principal causes was the ‘lack of clarity over the status of these episcopal princedoms.’[10]

What did the Peace of Augsburg accomplish?

The Peace of Augsburg led to the partition of Germany into two separate confessional blocs, one Catholic and the other Protestant, even though they all inhabited the Holy Roman Empire. It sought to establish a balance of power between them to ensure peace in the Empire. The settlement did succeed in establishing a balance of power in Germany. Still, it was never a stable one, and it only lasted so long because the Hapsburgs were distracted elsewhere. The Augsburg Treaty had effectively partitioned not only the Holy Roman Empire but also Christendom.[11]

After Augsburg's Peace, Germany was composed of two separate confessions that did not trust each other and saw each other as heretics. They both sought to gain an advantage over the other and increase their territory at the other's expense. Augsburg's settlement did end a war, but it also copper-fastened the division of the Empire into a Catholic and a Protestant bloc. When the balance of power broke down in 1618, these two mutually hostile religions began a war that was unprecedented in its loss of life and destruction.[12]

Was the Peace of Augsburg successful?

The Peace of Augsburg was intended to give Germany a lasting peace that would prevent future religious wars. The settlement was successful because it did prevent a general religious war in Germany and Central Europe until 1618. However, Augsburg's settlement in 1555 was fundamentally unstable, and its eventual failure was almost guaranteed. Those who drafted the treaty failed to recognize that the growth of Calvinism would destabilize the agreement and increase sectarian tensions in the Empire. Because the terms of the treaty did not cover them, they often worked against it, which led to Bohemia's conflict that triggered the Thirty Years War.

The settlement failed to resolve the episcopal principalities' status whose bishops had converted to Lutheranism, which was to poison relations between both sides for decades. Perhaps the most significant failure of the settlement was that it created two mutually hostile blocs. There was no mechanism designed by the settlement to defuse tensions or resolve conflicts. This led to the collapse of the Peace of Augsburg and the Thirty Years War, one of the greatest tragedies in Europe’s long history.


  1. Hale, JR, Reformation Europe (Pelican, London, 1998), p 134
  2. Cameron, Euan. The European Reformation (Second ed.) (Oxford, Oxford University Press, 2002), p. 113
  3. Von Friedeburg, Robert. "Cuius Regio, Eius Religio: The Ambivalent Meanings of State Building in Protestant Germany, 1555–1655." In Diversity and Dissent: Negotiating Religious Difference in Central Europe, 1500-1800, edited by Louthan Howard, Cohen Gary B., and Szabo Franz A. J., 73-91. Berghahn Books, 2011
  4. Elliot, J.H. Imperial Spain 1469–1716. Penguin Books (New York: 2002), p. 208
  5. Hale, p. 134
  6. Von Friedneburg, p 76
  7. Hale, p. 117
  8. Holborn, Hajo. A History of Modern Germany, The Reformation (Princeton: Princeton University Press), p. 195
  9. Wilson, Peter, The Thirty Years War: Europe's Tragedy. London: Belknap Press, 2011), p. 67
  10. Wilson. p 67
  11. Hale, p. 118
  12. Wilson, p. 656

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