Bernard II, who is regarded as the greatest of the Billungers, has expanded the powers of the duke in Saxony.

Originally a supporter of Emperor Henry II, Bernard had accompanied him into Poland and negotiated the treaty of Bautzen of 1018.

He revolts in 1019–102 and gains the recognition of the tribal laws of Saxony, something his father had failed to do.

Bernard II returns now to war with the Slavs (Obodrites and Lutici) and draws them into his sphere of power and influence through their leader, Godescalc (Gottschalk).

Nako, having turned to Christianity after his defeat in the Battle of Recknitz in 955, had established his seat at Mecklenburg.

His sons Mstivoj and Mstidrag and grandsons Mstislaw and Udo are mostly associated with the Slavic uprising of 983.

All of them had either abandoned Christianity or were "bad Christians" (at least for a time).

Udo was a bad Christian (male christianus according to Adam of Bremen) whose own father, Mistiwoi, had renounced the new religion for the old Slavic paganism.

Udo had sent his son to be educated at the monastery of St. Michael at Lenzen and later at Lüneburg.

After a Saxon murdered Udo in 1028, Gottschalk had renounced Christianity and assumed the leadership of the Liutici to avenge his father, killing many Saxons before Duke Bernard II of Saxony defeated and captured him; his lands had gone to Ratibor of the Polabians.

Reconverted to Christianity, Gottschalk had been released and sent to Denmark with many of his people to serve King Cnut in his wars with Norway.

Sveyn Estridson, Jarl of Denmark, desired independence from King Magnus I of Norway in 1042.

Because Magnus is supported by his brother-in-law, Bernard II, Sveyn achieves an alliance with the Obotrites through the mediation of Gottschalk.

However, the Obotrite chief Ratibor is killed in a siege by Magnus in 1043.

In an attempt to avenge their father, his sons are killed in the same year in a battle at Lürschau Heath on 28 September.

The death of Ratibor and his sons allows Gottschalk, who marries Sveyn's daughter Sigrid, to seek the inheritance of his father Udo as Prince of the Obodrites.

…their active trading port of Reric/Veligrad (modern Mecklenburg).

Under the reign of their western duke Gottschalk, the Obrodites control the area east of Saxony and west of the Lutici.

The Slavic groups inhabiting the lands between the Elbe and Oder Rivers are often described by Germanic sources as Wends.

The Veletians had in the late tenth century been continued in part by the Lutici.

By the mid-eleventh century, the Lutici have successfully united several local Slavic peoples and now dominate the area north of Lusatia to the Black Sea.

The Obrotrite prince Gottschalk had conquered the Circipani and Kessini during the so-called Liutizci Civil War (Lutizischer Bruderkrieg) of 1057.

He has secured the territory through the building of new fortresses; the old fortifications of the conquered tribes have been removed.

He nurtures alliance with his Christian neighbors, Scandinavian and German, and has joined in an alliance with Duke Bernard and King Magnus to defeat the Liutici in battle.

He has subdued the Liutici and the diocese of Bremen pays him tribute.

Allied with the Lutici, the Obotrites murder Gottschalk in a 1066 rebellion, capturing the castle of Lenzen and forcing his sons Henry and Budivoj to flee to Denmark and to Lüneburg respectively.

John, the bishop of Mecklenburg, is captured and sacrificed at Radgosc in the course of the rebellion.

As a consequence, the bishop of Halberstadt and the emperor will sack and destroy Radgosc in subsequent campaigns.

Burchard II, Bishop of Halberstadt, had in 1057 become provost of the church of SS Simon and Judas in Goslar.

In 1059, through the intervention of his uncle, Anno, he had succeeded Burchard I in the diocese of Halberstadt.

In 1062, it had been the decision of a German-Italian synod held at Augsburg to send Burchard, high in the favor of the regent of the young Henry IV, Empress Agnes, to Rome to mediate a disputed Papal election between the legitimate Pope Alexander II and the Antipope Honorius II.

Although the German crown stood by Honorius, Burchard had vowed to stand by Hildebrand, the great Papal reformer, and supported Alexander.

In gratitude, Alexander had bestowed on Burchard the coveted pallium.

In the dead of winter 1067–1068, Burchard, crossing frozen marshland, invades the country of the Lutici, razes the pagan temple at Radgosc, and returns to Saxony riding the sacred black horse.

Henry recovers the confiscated Saxon estates by treaty in 1142, but Conrad wins a partial victory in this year by depriving the Welfs of the Bavarian duchy.

Frederick Barbarossa, still fuming over Henry the Lion’s refusal of military service during his failed expedition into Lombardy, robs Henry of most of his possessions in 1180.

Taking advantage of the hostility of other German princes to Henry, who had successfully established a powerful and contiguous state comprising Saxony, Bavaria and substantial territories in the north and east of Germany, Frederick has Henry tried in absentia for insubordination by a court of bishops and princes in 1180.

Declaring that Imperial law overrules traditional German law, the court has Henry stripped of his lands and declares him an outlaw.

Frederick now invades Saxony with an Imperial army to bring his cousin to his knees.

The princes of Mecklenburg—a hilly, lake-filled, glaciated plain with an irregular coastline and several islands located on the Baltic Sea between the Elbe and Oder rivers—vassals of the Holy Roman Empire from the twelfth century, become dukes in 1348.

Strictly speaking, Mecklenburg’s princely dynasty is descended linearly from the princes (or kings) of a Slavic tribe, the Obotrites, and had its original residence in a castle (Mecklenburg) in Dorf Mecklenburg (Mikelenburg) close to Wismar.

As part of a feudal union under German law from 1160—at first under the Saxons—Mecklenburg is granted imperial immediacy in 1348 and its princely rulers styled Dukes of Mecklenburg.