Lower Saxony, which includes most of the land between the Rhine and the Elbe rivers and is composed of the regions of Brunswick, or Braunschweig, and Lueneburg, was originally part of the old duchy of Saxony. The duchy of Saxony was in existence between the 9th and 12th centuries.
The medieval dukedom was ruled by the Cherusker and the Chauken, whose lands were later absorbed by the Saxons. Between the 5th and 7th centuries, the Saxons expanded southward to the Hartz region. They were unified by Duke Widukind, and they fought for over thirty years against Charlemagne. After Charlemagne destroyed the land and executed 4500 leaders near Verden, Widukind submitted and the Saxons were converted to Christianity.
Winifred, a missionary from England, brought Christianity to the German Saxons and became known as the "Apostle of the Germans." After the decline of the Frankish dynasty, a Saxon duke became king of Germany as Henry I in 918. His son, Otto I, conquered Italy and was crowned Holy Roman Emperor. Saxon dukes became known as the Welfs, whose most famous descendant was Henry the Lion, who was one of the most important colonizers of Old Prussia and Pomerania.
In the 12th century, Henry the Lion, made Brunswick his capital and built the castle Dankwarderode. After he lost the dukedoms of Saxony and Bavaria, Henry named his grandson, Otto the Child, heir to the Welfen possessions. These lands were divided into three dukedoms: Braunschweig-Wolfenbuettel, Braunschweig-Lueneburg, and Calenberg-Goettingen.
Henry the Younger (1489-1568), made the duchy of Braunschweig-Wolfenbuettel politically strong. However, he introduced the law of primogeniture (Succession of the Firstborn), which protected the integrity of his land-holdings. His affair with the lady-in-waiting Eva von Trott, who bore him ten children (and whose funeral he faked!) forced him to leave the country for a time. Henry's Protestant son Julius, founded the university of Helmstedt, and the Dukes of Calenberg were strong supporters of the Reformation. In the 17th century, the dukedoms of Braunschweig-Lueneburg and Calenberg-Goettingen were united, and the Saxon dukes moved to Hanover. The Saxon dukes attempted to remain neutral in the Thirty Years War, but the princedoms of Celle and Lueneburg were ravaged by marauding Swedish and imperial troops. In the 19th century, Brunswick became a part of the kingdom of Hanover, and the Saxon lands became a part of the German Empire after the Unification of Germany in 1871.