Planned since 955 and established in 967, the 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.

In political respect the Erzstift, the archiepiscopal and capitular temporalities, had gained imperial immediacy as a prince-archbishopric in 1180.

After being secularised, the state was transformed into the Duchy of Magdeburg, a hereditary monarchy in personal union with Brandenburg.

[2] Otto immediately set to work to establish an archbishopric in Magdeburg, for the stabilisation through Christianisation of the eastern territories.

The new archdiocese was close to the unsecured border regions of the Holy Roman Empire and Slavic tribes, and was meant to promote Christianity among the many Slavs and others.

The first archbishop was Adelbert, a former monk of St. Maximin's at Trier,[3] afterwards a missionary bishop to the Ruthenians (Ruthenia), and Abbot of Weissenburg in Alsace.

The archdiocesan area of Magdeburg was rather small; it comprised the Slavonic districts of Serimunt, Nudizi, Neletici, Nizizi, and half of northern Thuringia, which Halberstadt resigned.

[5] Among successors worthy of mention are the zealous Gero (1012–23) and St. Norbert, prominent in the 12th century (1126–34), the founder of the Premonstratensian order.

Wichmann sided with the emperor in the Great Saxon Revolt and was rewarded by recognising the archepiscopal and the cathedral capitular temporalities as a state of imperial immediacy within the Holy Roman Empire, thus Wichmann was the first to add the title secular prince to his ecclesiastical archbishop.

In 1208 he began to build the present Cathedral of Magdeburg, which was only consecrated in 1263, and never entirely finished; Günther I (1277–79) hardly escaped a serious war with the Margrave Otto IV, who was incensed because his brother Eric of Brandenburg had not been elected archbishop.

Cardinal Albert of Brandenburg (1513–45), on account of his insecure position, as well as being crippled by a perpetual lack of funds, gave some occasion for the spread of Lutheranism in his diocese, although himself opposing the Reformation.

It is not true that he became a Lutheran and wished to retain his see as a secular principality, and just as untrue that in the Kalbe Parliament in 1541 he consented to the introduction of the Reformation in order to have his debts paid.

His successors were the zealous Catholics John Albert of Brandenburg-Ansbach (1545–1550), who however could accomplish very little, and Frederick IV of Brandenburg, who died in 1552.

Administrators who were secular princes now took the place of the archbishop, and they, as well as the majority of the cathedral chapter and the inhabitants of the archdiocese, were usually Protestant.