Margaret of Münsterberg, the fourth child of the Duke Henry the Elder of Münsterberg (1448–1498) and his wife Ursula of Brandenburg (1450–1508), had received a strictly religious education from her parents.

In 1494, she had married Prince Ernest I of Anhalt from the line of Anhalt-Zerbst.

After the other lines of the Anhalt family died out, Ernest had been able to reunite the Principality of Anhalt for the first time since 1252.

They took up their residence in Dessau.

Ernest died in 1516 and Margaret took up the regency of the principality for her underage sons John IV and George III.

Her regency is characterized by thrift and deep religiosity.

She strictly opposes the Reformation, which had started spreading from neighboring Wittenberg in 1517.

She has found an ally in her first cousin Albert, who is Archbishop of Magdeburg.

In 1525, Margaret launched the League of Dessau, an alliance of Catholic princes opposed to the Reformation.

Her oldest son, John V, who had been co-regent since 1522 and her second son George, who will later become co-ruler as George III, had already built up contacts with Martin Luther, but they will not lead their Principality into the Reformation until 1534 (with George III as the driving force), well after Margaret's death.

The League is founded in Dessau on July 19, a few weeks after the Battle of Frankenhausen in Thuringia, where the peasant revolutionaries had been overpowered.

This suggested to the Catholic sovereigns that a crackdown against Protestantism should be possible.

Although Margaret has a mostly friendly attitude towards Martin Luther himself, the princess fears a repeat of the peasant uprisings in her own country, so she convenes the League, against the wishes of her sons.

Its goals are to stop both the rebellion and the proliferation of Martin Luther's teachings.

Members of the alliance include Duke George of Saxony, Elector Joachim I Nestor of Brandenburg, Archbishop Albert of Mainz and Magdeburg, Duke Eric I of Brunswick-Calenberg-Göttingen, and Duke Henry V of Brunswick-Wolfenbüttel.

The League of Dessau is limited within Anhalt to the Principality of Anhalt-Dessau, because …

…the neighboring principalities of Anhalt-Köthen and …

…Anhalt-Bernburg had converted to Lutheranism in 1525 and 1526, as the second and third countries in the world to do so, after the Electorate of Saxony.

The League of Dessau does not have much effect: it is unable to motivate the Catholic princes in the south of the Holy Roman Empire to join.

During the First Diet of Speyer in 1526, followers of both faiths attempt to agree on a political compromise.

The Edict of Worms is repealed.

A decision is taken to tolerate the new faith until a Synod can resolve the religious differences.