Saxony, Duchy of

a tribal duchy of the Saxons in northern Germany that originated in the late ninth century.

In 919 the Saxon duke Henry became King Henry I of Germany and thereby founded the Saxon dynasty. The efforts of the emperors of the Franconian dynasty, particularly Henry IV, to consolidate the royal domain in Saxony led to the Saxon Uprising of 1073–75. The Duchy of Saxony grew stronger under the rule of Lothair of Supplinburg, who became King Lo-thair III of Germany in 1125, and especially under Heinrich der Lowe (Henry the Lion) of the House of Welf. The Polabian Slavs bordered Saxony on the east, and the duchy became one of the principal centers of German aggression against them.

The Duchy of Saxony disintegrated into a number of feudal domains after the fall of Heinrich der Löwe in 1180. From 1235 the greater part of its territory consisted of the Duchy of Braun-schweig-Lüneburg, which subsequently became the Electorate of Hanover. Part of the territory of the former Duchy of Saxony—the Electorate of Saxe-Wittenberg—was transferred in 1423 to the feudal House of Wettin, whose possessions gradually came to be known as Saxony.