The Diet of Augsburg were the meetings of the Imperial Diet  of the Holy Roman Empire

Holy Roman Empire

The Holy Roman Empire was a realm that existed from 962 to 1806 in Central Europe.It was ruled by the Holy Roman Emperor. Its character changed during the Middle Ages and the Early Modern period, when the power of the emperor gradually weakened in favour of the princes...

 in the German city of Augsburg

Augsburg

Augsburg is a city in the south-west of Bavaria, Germany. It is a university town and home of the Regierungsbezirk Schwaben and the Bezirk Schwaben. Augsburg is an urban district and home to the institutions of the Landkreis Augsburg. It is, as of 2008, the third-largest city in Bavaria with a...

. There were many such sessions, but the three meetings during the Reformation

Protestant Reformation

The Protestant Reformation was a 16th-century split within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. The efforts of the self-described "reformers", who objected to the doctrines, rituals and ecclesiastical structure of the Roman Catholic Church, led...

 and the ensuing religious wars between the Roman Catholic emperor

Holy Roman Emperor

The Holy Roman Emperor is a term used by historians to denote a medieval ruler who, as German King, had also received the title of "Emperor of the Romans" from the Pope...

 Charles V

Charles V, Holy Roman Emperor

Charles V was ruler of the Holy Roman Empire from 1519 and, as Charles I, of the Spanish Empire from 1516 until his voluntary retirement and abdication in favor of his younger brother Ferdinand I and his son Philip II in 1556.As...

 and the Protestant Schmalkaldic League

Schmalkaldic League

The Schmalkaldic League was a defensive alliance of Lutheran princes within the Holy Roman Empire during the mid-16th century. Although originally started for religious motives soon after the start of the Protestant Reformation, its members eventually intended for the League to replace the Holy...

 in the early 16th century are especially noteworthy.

The session of 1530 attempted to calm rising tensions over Protestantism

Protestantism

Protestantism is one of the three major groupings within Christianity. It is a movement that began in Germany in the early 16th century as a reaction against medieval Roman Catholic doctrines and practices, especially in regards to salvation, justification, and ecclesiology.The doctrines of the...

. After the Edict of Worms had condemned Lutheranism

Lutheranism

Lutheranism is a major branch of Western Christianity that identifies with the theology of Martin Luther, a German reformer. Luther's efforts to reform the theology and practice of the church launched the Protestant Reformation...

, problems of enforcement emerged during the 1520s, as Charles V's wars against France and commitments in the rest of his empire prevented him from focusing on German religious problems. In 1529, however, he signed a successful peace treaty with France. After these successes, Charles aimed to assert his control over what he saw as German religious heresies. It brought forth the Augsburg Confession

Augsburg Confession

The Augsburg Confession, also known as the "Augustana" from its Latin name, Confessio Augustana, is the primary confession of faith of the Lutheran Church and one of the most important documents of the Lutheran reformation...

, or Confessio Augustana, a central document of Lutheranism that was presented to emperor Charles V.

After his victory over the Schmalkaldic League, Charles V convened the Diet of 1547/48 (geharnischter Reichstag), where the Augsburg Interim

Augsburg Interim

The Augsburg Interim is the general term given to an imperial decree ordered on May 15, 1548, at the 1548 Diet of Augsburg, after Charles V, Holy Roman Emperor, had defeated the forces of the Schmalkaldic League in the Schmalkaldic War of 1546/47...

 was proclaimed. This attempt to give Catholicism the priority was rejected by many princes, though, and a resolution of the confessional tensions was only achieved at the session on 1555, where the Peace of Augsburg

Peace of Augsburg

The Peace of Augsburg, also called the Augsburg Settlement, was a treaty between Charles V and the forces of the Schmalkaldic League, an alliance of Lutheran princes, on September 25, 1555, at the imperial city of Augsburg, now in present-day Bavaria, Germany.It officially ended the religious...

 was concluded. The treaty acknowledged the Confessio Augustana and codified the cuius regio, eius religio

Cuius regio, eius religio

Cuius regio, eius religio is a phrase in Latin translated as "Whose realm, his religion", meaning the religion of the ruler dictated the religion of the ruled...

principle, which gave each prince the power to decide the religion of his subjects.

The decrees of the Council of Trent

Council of Trent

The Council of Trent was the 16th-century Ecumenical Council of the Roman Catholic Church. It is considered to be one of the Church's most important councils. It convened in Trent between December 13, 1545, and December 4, 1563 in twenty-five sessions for three periods...

were acknowledged in Italy, Portugal, Poland, and by the Catholic princes of Germany at the Diet of Augsburg held in 1566.