The Schmalkaldic League: Reformation War

War council during the Schmalkaldic War
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The Schmalkaldic League, an alliance of Lutheran princes and cities that pledged to protect each other from any religiously motivated attack lasted for sixteen years. The Reformation had further divided Europe already fragmented by cultural, economic and political differences. In the Holy Roman Empire, which covered much of central Europe, the newly Lutheran princes clashed with their Emperor: he was the secular head of the Catholic Church and they were part of a heresy. They banded together to survive.

The Empire Divides

In the mid-1500s the Holy Roman Empire was a piecemeal grouping of over 300 territories, which varied from large dukedoms to single cities; although largely independent, they all owed some form of loyalty to the Emperor. After Luther ignited a massive religious debate in 1517, via the publication of his 95 Theses, many German territories adopted his ideas and converted away from the existing Catholic Church. However, the Empire was an intrinsically Catholic institution, and the Emperor was the secular head of a Catholic Church that now regarded Luther's ideas as heresy. In 1521 Emperor Charles V pledged to remove the Lutherans (this new branch of religion was not yet called Protestantism) from his kingdom, with force if necessary.

There was no immediate armed conflict. The Lutheran territories still owed allegiance to the Emperor, even though they were implicitly opposed to his role in the Catholic Church; he was, after all, the head of their empire. Likewise, although the Emperor was opposed to the Lutherans, he was hamstrung without them: the Empire had powerful resources, but these were split amongst hundreds of states. Throughout the 1520's Charles needed their support - militarily, politically and economically - and he was thus prevented from acting against them. Consequently, Lutheran ideas continued to spread amongst the German territories.

In 1530, the situation changed. Charles had renewed his peace with France in 1529, temporarily driven the Ottoman forces back, and settled matters in Spain; he wanted to use this hiatus to reunite his empire, so it was ready to face any renewed Ottoman threat. Additionally, he had just returned from Rome having been crowned Emperor by the Pope, and he wanted to end the heresy. With the Catholic majority in the Diet (or Reichstag) demanding a general church council, and the Pope preferring arms, Charles was prepared to compromise. He asked the Lutherans to present their beliefs at a Diet, to be held in Augsburg.

The Emperor Rejects

Philip Melanchthon prepared a statement defining the basic Lutheran ideas, which had now been refined by nearly two decades of debate and discussion. This was the Confession of Augsburg, and it was delivered in June 1530. However, for many Catholics, there could be no compromise with this new heresy, and they presented a rejection of the Lutheran Confession entitled The Confutation of Augsburg. Despite it being very diplomatic - Melanchthon had avoided the most contentious issues and focused on areas of probable compromise - the Confession was rejected by Charles. He instead accepted the Confutation, consented to a renewal of the Edict of Worms (which banned Luther's ideas), and gave a limited period for the 'heretics' to reconvert. The Lutheran members of the Diet left, in a mood which historians have described as both disgust and alienation.

The League Forms

In a direct reaction to the events of Augsburg two leading Lutheran princes, Landgrave Philip of Hesse and Elector John of Saxony, arranged a meeting at Schmalkalden, in the December of 1530. Here, in 1531, eight princes and eleven cities agreed to form a defensive league: if one member were attacked because of their religion, all the others would unite and support them. The Confession of Augsburg was to be taken as their statement of faith, and a charter was drawn up. Additionally, a commitment to provide troops was established, with a substantial military burden of 10,000 infantry and 2,000 cavalries being split amongst the members.

The creation of leagues was common in the early modern Holy Roman Empire, especially during the Reformation. The League of Torgau had been formed by Lutherans in 1526, to oppose the Edict of Worms, and the 1520s also saw the Leagues of Speyer, Dessau, and Regensburg; the latter two were Catholic. However, the Schmalkaldic League included a large military component, and for the first time, a powerful group of princes and cities appeared to be both openly defiant of the Emperor, and ready to fight him.

Some historians have claimed that the events of 1530-31 made an armed conflict between the League and the Emperor inevitable, but this might not be the case. The Lutheran princes were still respectful of their Emperor and many were reluctant to attack; indeed, the city of Nuremberg, which remained outside the League, as opposed to challenging him at all. Equally, many Catholic territories were loath to encourage a situation whereby the Emperor could restrict their rights or march against them, and a successful attack on the Lutherans could establish an unwanted precedent. Finally, Charles still wished to negotiate a compromise.

War Averted by More War

These are moot points, however, because a large Ottoman army transformed the situation. Charles had already lost large parts of Hungary to them, and renewed attacks in the east prompted the Emperor to declare a religious truce with the Lutherans: the 'Peace of Nuremberg.' This canceled certain legal cases and prevented any action being taken against the Protestants until a general church council had met, but no date was given; the Lutherans could continue, and so would their military support. This set the tone for another fifteen years, as Ottoman - and later French - pressure forced Charles to call a series of truces, interspersed with declarations of heresy. The situation became one of intolerant theory, but tolerant practice. Without any unified or directed Catholic opposition, the Schmalkaldic League was able to grow in power.


One early Schmalkaldic triumph was the restoration of Duke Ulrich. A friend of Philip of Hesse, Ulrich had been expelled from his Duchy of Württemberg in 1919: his conquest of a previously independent city caused the powerful Swabian League to invade and eject him. The Duchy had since been sold to Charles, and the League used a combination of Bavarian support and Imperial need to force the Emperor to agree. This was seen as a major victory among the Lutheran territories, and the League's numbers grew. Hesse and his allies also courted foreign support, forming relationships with the French, English, and Danish, who all pledged varying forms of aid. Crucially, the League did this while maintaining, at least an illusion of, their loyalty to the emperor.

The League acted to support cities and individuals who wished to convert to Lutheran beliefs and harass any attempts to curb them. They were occasionally pro-active: in 1542 a League army attacked the Duchy of Brunswick-Wolfenbüttel, the remaining Catholic heartland in the north, and expelled its Duke, Henry. Although this action broke a truce between the League and the Emperor, Charles was too embroiled in a new conflict with France, and his brother with problems in Hungary, to react. By 1545, all of the northern Empire was Lutheran, and numbers were growing in the south. While the Schmalkaldic League never included all of the Lutheran territories - many cities and princes remained separate - it did form a core amongst them.

The Schmalkaldic League Fragments

The decline of the League began in the early 1540s. Philip of Hesse was revealed to be a bigamist, a crime punishable by death under the Empire's legal Code of 1532. Fearing for his life, Philip sought an Imperial pardon, and when Charles agreed, Philip's political strength was shattered; the League lost an important leader. Additionally, external pressures were again pushing Charles to seek a resolution. The Ottoman threat was continuing, and almost all of Hungary was lost; Charles needed the power that only a united Empire would bring. Perhaps more importantly, the sheer extent of Lutheran conversions demanded Imperial action - three of the seven electors were now Protestant and another, the Archbishop of Cologne, appeared to be wavering. The possibility of a Lutheran empire, and maybe even a Protestant (although uncrowned) Emperor, was growing.

Charles's approach to the League had also changed. The failure of his frequent attempts at negotiation, although the 'fault' of both sides, had clarified the situation - only war or tolerance would work, and the latter was far from ideal. The Emperor began to seek allies amongst the Lutheran princes, exploiting their secular differences, and his two greatest coups were Maurice, the Duke of Saxony, and Albert, Duke of Bavaria. Maurice hated his cousin John, who was both the Elector of Saxony and a leading member of the Schmalkaldic League; Charles promised all of John's lands and titles as a reward. Albert was persuaded by an offer of marriage: his eldest son for the Emperor's niece. Charles also worked to end the League's foreign support, and in 1544 he signed the Peace of Crèpy with Francis I, whereby the French King agreed not to ally with Protestants from within the Empire. This included the Schmalkaldic League.

The End of the League

In 1546, Charles took advantage of a truce with the Ottomans and gathered an army, drawing troops from across the Empire. The Pope also sent support, in the form of a force led by his grandson. While the League was quick to muster, there was little attempt to defeat any of the smaller units before they had combined under Charles. Indeed, historians often take this indecisive activity as evidence that the League had a weak and ineffectual leadership. Certainly, many members distrusted each other, and several cities argued about their troop commitments. The League's only real unity was Lutheran belief, but they even varied in this; additionally, the cities tended to favor simple defense, some princes wanted to attack.
The Schmalkaldic War was fought between 1546-47. The League may have had more troops, but they were disorganized, and Maurice effectively split their forces when his invasion of Saxony drew John away. Ultimately, the League was beaten easily by Charles at the Battle of Mühlberg, where he crushed the Schmalkaldic army and captured many of its leaders. John and Philip of Hesse were imprisoned, the Emperor stripped 28 cities of their independent constitutions, and the League was finished.

The Protestants Rally

Of course, victory on the field of battle doesn't translate directly into success elsewhere, and Charles swiftly lost control. Many of the conquered territories refused to reconvert, the papal armies withdrew to Rome, and the Emperor's Lutheran alliances swiftly fell apart. The Schmalkaldic League may have been powerful, but it was never the sole Protestant body in the Empire, and Charles's new attempt at religious compromise, the Augsburg Interim, displeased both sides greatly. The problems of the early 1530s reappeared, with some Catholics loathe to crush the Lutherans in case the Emperor gained too much power. During the years 1551-52, a new Protestant League was created, which included Maurice of Saxony; this replaced its Schmalkaldic predecessor as a protector of the Lutheran territories and contributed to the Imperial acceptance of Lutheranism in 1555.

A Timeline for the Schmalkaldic League

1517 - Luther begins a debate on his 95 Theses.
1521 - The Edict of Worms bans Luther and his ideas from the Empire.
1530 - June - The Diet of Augsburg is held, and the Emperor rejects the Lutheran 'Confession.'
1530 - December - Philip of Hesse and John of Saxony call a meeting of Lutherans in Schmalkalden.
1531 - The Schmalkaldic League is formed by a small group of Lutheran princes and cities, to defend themselves against attacks on their religion.
1532 - External pressures force the Emperor to decree the 'Peace of Nuremberg'. Lutherans are to be temporarily tolerated.
1534 - Restoration of Duke Ulrich to his Duchy by the League.
1541 - Philip of Hesse is given an Imperial pardon for his bigamy, neutralizing him as a political force. The Colloquy of Regensburg is called by Charles, but negotiations between Lutheran and Catholic theologians fail to reach a compromise.
1542 - The League attacks the Duchy of Brunswick-Wolfenbüttel, expelling the Catholic Duke.
1544 - Peace of Crèpy signed between the Empire and France; the League lose their French support.
1546 - The Schmalkaldic War begins.
1547 - The League is defeated at the Battle of Mühlberg, and its leaders are captured.
1548 - Charles decrees the Augsburg Interim as a compromise; it fails.
1551/2 - The Protestant League is created to defend the Lutheran territories.

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Wilde, Robert. "The Schmalkaldic League: Reformation War." ThoughtCo, Aug. 28, 2020, Wilde, Robert. (2020, August 28). The Schmalkaldic League: Reformation War. Retrieved from Wilde, Robert. "The Schmalkaldic League: Reformation War." ThoughtCo. (accessed June 10, 2023).