He was the son of Erling Skakke, a Norwegian nobleman who earned his reputation crusading with Rögnvald Kali Kolsson, the earl of Orkney.
His father Erling took the title of earl and held the real power since Magnus was a minor.
In 1168 Olav and his men ventured south to the Oslofjord area, but were there defeated in battle at Stanger in Våler.
[4] Magnus' reign saw the arrival in Norway of Sverre Sigurdsson, who claimed the throne for himself as an allegedly illegitimate son of a previous king.
[2] Several more years of warfare ended with Magnus' defeat and death in the Battle of Fimreite on June 15, 1184.
The background for these conflicts was the unclear Norwegian succession laws, social conditions and the struggle between Church and King.