He was only thirteen when he succeeded to the Duchy of Saxony in 1142 and had to wait until 1154 before Bavaria, taken from his father, was restored to him. In 1150 he fathered a child, Mechtild, by his concubine, Ida von Bliescastel and, also about 1150, he married Klementia von Zaehringen; after the birth of two children, he divorced her in 1162. On 1 February 1168, in Minden, he married Matilda of England, daughter of King Henry II. After her death, he is supposed to have married his concubine, Ida von Bliescastel.
Involved with extermination of the pagans, he obtained the county of Mecklenburg and, in 1158, forced Adolf II of Holstein to hand to him the city of Luebeck which was then developed into an important trading city. However, his power and ambitious designs roused against him a league of princes in 1166; however, he was able to survive them until the Emperor, alarmed , deprived him of his dominions and placed him under the ban of the empire in 1180.
Reconciled with the next Emperor, Heinrich VI, he encouraged agriculture as well as the commerce of Hamburg and Luebeck and founded the city of Munich.
 

Source: Leo van de Pas