Magnus IV "The Blind" Sigurdsson King Of Norway
- Born: Abt 1115, Norway
- Marriage: Kristin Knudsdatter in 1132
- Died: 12 Nov 1139, Battle of Hvaler, Østfold, Norway about age 24
Magnus the Blind, (Norwegian Magnus den Blinde), joint ruler of Norway (1130-35), with Harald IV, whose abortive attempt (1137-39) to wrest sovereignty from Inge I Haroldsson and Sigurd II, sons of Harald IV, ended the first epoch in the period of Norwegian civil wars (1130-1240). The son of the Norwegian king Sigurd I Magnusson, Magnus succeeded to the throne jointly with Harald IV in 1130.
In 1134 war broke out between the two rulers, and the following year Magnus was seized by Harald, maimed, blinded, and put in a monastery. He was liberated in 1137 by Sigurd Slembi, who had slain Harald the year before but could not gain support for his own claim to the throne and hoped, instead, to install Magnus as king. Although Magnus won the allegiance of many chieftains who honoured him as the son of Sigurd I, his forces were defeated twice by the backers of Inge and Sigurd II.
In 1139 Magnus began another attack on the forces of Inge and Sigurd II, this time from Denmark in alliance with Sigurd Slembi, but he was killed in the battle.
Also: Magnus was the son of Sigurd Jorsalfar and became king when Sigurd died. At the same time his father's brother, Harald Gille, was declared king and that ended in quarrels between Magnus and and his uncle Harald. Magnus was married to Kristin Knudsdatter and so became involved into the fight for the Danish throne. King Erik Emune had to flee from Denmark and lived some time at Magnus place, but soon there was quarrels and Erik went on to Harald Gille.
The quarrels between Magnus and Harald Gille soon lead to open adversary and soon there was war. Magnus was victorious in the beginning and Harald fled to Denmark. Harald Gille got men and arms in Denmark and returned to Norway. He captured Magnus in Bergen and Magnus was blinded, castrated and the man of Harald axed one foot of Magnus so that he never could become king again. Then, he was sent to a monastery at Munkholmen near Nidaros (today's Trondheim). Sigurd Slembe, a son of Magnus Barfot, gathered men around him and demanded to be king as he was son of Magnus Barfot. That led to war between Harald Gille and Sigurd and in 1137, Sigurd took Magnus out of the Monastery. Together, they fought against Harald, but were defeated and flew to Denmark. Magnus got help from Erik Emune in Denmark but was again defeated and finally fell in his final Battle at Hvaler. Magnus time as king started a time that is today known as fratricidal wars and lasted until 1228.
Magnus married Kristin Knudsdatter, daughter of Knud Eriksson Lavard and Ingeborg Mstislavsdatter, in 1132. (Kristin Knudsdatter was born about 1118.)