The Mecklenburg dukes, descended from the Slavic Obotrite princes, one of whom — Albert — was elected King of Sweden before his defeat by Margaret I.
The house descended from Niklot, prince of the Obotrites, a confederation of Slavic peoples on the Baltic coast who resisted German and Danish expansion in the twelfth century. Niklot died fighting Henry the Lion’s Wendish Crusade in 1160, but his descendants accepted Christianity and German overlordship and were recognised as hereditary lords, later dukes, of Mecklenburg — a rare case of a native Slavic dynasty surviving the conquest to rule as imperial princes into the twentieth century.
From their Baltic duchy the Mecklenburgs married into the royal houses of Scandinavia, which drew them into the politics of the northern kingdoms.
In 1363 Swedish magnates in revolt against King Magnus IV turned to Duke Albert II of Mecklenburg, whose wife was a Swedish royal princess, and the next year his son Albert was elected and crowned King of Sweden. His reign depended on the great nobles who had raised him, and his attempts to build royal and Mecklenburg power against them steadily lost him support.
When he moved to seize the estates of the powerful magnate Bo Jonsson Grip, the Swedish council offered the regency to Margaret I of Denmark. Albert marched against her and was decisively beaten and taken prisoner at Åsle in 1389.
Albert’s defeat delivered Sweden to Margaret and cleared the way for the Kalmar Union of 1397; after years of captivity he renounced his claim and returned to rule in Mecklenburg, where he died in 1412. The bitterness of the war lived on in the Baltic, where Mecklenburg-backed privateers, the Victual Brothers, plagued shipping for years.
The ducal house itself endured far longer than its Swedish adventure: the Mecklenburgs ruled their German duchies until the fall of the monarchies in 1918.