After the fall of Harald Hardrada came the more peaceful reign of Olaf the Calm, who ruled Norway for 27 years. In his reign, Norway achieved considerable wealth. After the death of Olaf, in 1095, Norway was again divided into two states, and infinite quarrels arose again, until one of the King, Magnus III, became the sovereign of united Norway again. He made expeditions to foreign countries, conquered the Hebrides and Orkney Islands and the English Isle of Man and fell in Ireland in 1103. He was succeeded by his sons, Eric and Sigurd. The first wise government contributed to the peaceful accession to Norway of new areas, built churches, monasteries, etc. Sigurd, on the contrary, was distinguished by the brave, restless spirit of the ancient Vikings. In 1107 – 1111 he embarked on a crusade in the Holy Land and returned with many plundered treasures. In Jerusalem, he pledged before the patriarch to arrange a bishopric in Norway and establish church tithe, which he fulfilled.
After his death (1130) a long period of internecine wars begins. The state was sometimes fragmented between several sovereigns, sometimes united under the rule of one. The clergy managed to take advantage of the time of troubles in order to expand their rights and privileges. This greatly weakened the power of the king. The Norwegian aristocracy became more and more distant from the people and, after the introduction of Christianity, began to draw closer to the clergy, seeking, collectively with it, to concentrate in their hands the government of the country.
In 1161, during the reign of Hakon II, Norway was visited by a papal legate, who forced him to recognize the prohibition of marriage of priests and introduced other reforms. In Bergen, he anointed the reign of 8-year-old Magnus, elected king in 1162. Magnus came from Harald I by mother; the church, having consecrated his inheritance rights, gave an opportunity to a number of descendants of the daughters of the kings to lay claims to the Norwegian throne. In 1174, Conus Magnus, according to the conviction of Eystein, the archbishop of Nidaros, promulgated a law called the Golden Pen’s Letter and granted the Norwegian clergy very large rights. Magnus, who called himself the king of God in grace, promised to set tithe in favor of the church, refused any interference in the election of bishops and other church dignitaries. Thus, the appointment of the king by the national assembly was replaced in Norway by the dictatorship of the clergy and the coronation. This was explained by the fact that every konung received Norway as if in flax from St. Olaf.
After this an uprising took place. A struggle arose between two parties, one of which was called Birch-legged ( Birkebeiners ), and the other was Krivozvezlova (Bugleroi), from a curved bishop’s baton. The struggle continued for more than a century and caused a number of coups. The Birkebeiners were already close to death when they were headed by the former priest Sverrir, an Icelander by birth, posing as the son of King Sigurd Munn. In 1184, Magnus was killed, and Sverrir was elected king.
Sources:
Brockhaus and Efron Encyclopedic Dictionary
Danielsen R., Durvik S., Grönli T., Helle K., Hovland E. History of Norway. From the Vikings to our days
History from the Vikings to Our Own Times
Khlevov A.A. The forerunners of the Vikings
Kuznetsov A.Ye. History of Norway
Keizer, Jacob Rudolph . Norges Historie