The civil war era in Norway (Norwegian: borgarkrigstida, borgarkrigstidi, borgerkrigstida or borgerkrigstiden) began in 1130 and ended in 1240.

In the absence of formal laws governing claims to rule, men who had proper lineage and wanted to be king came forward and entered into peaceful, if still fraught, agreements to let one man be king, set up temporary lines of succession, take turns ruling, or share power simultaneously.

When they reconciled in 1217, a more ordered and codified governmental system gradually freed Norway from wars to overthrow the lawful monarch.

The main criterion for being considered a worthy candidate for the throne was to be a descendant of Harald Fairhair through the male line—legitimate or illegitimate birth was not an issue.

Harald proved his case through an ordeal of fire, the common way of settling such claims at the time, and King Sigurd recognized him as his brother.

According to the sagas, Øystein and Sigurd Munn laid plans to depose their brother Inge and divide his share of the kingdom between them.

At the urging of his mother Ingrid Ragnvaldsdotter and the influential lendmann Gregorius Dagsson, Inge decided to strike first, at a meeting among the three kings in Bergen.

The choice fell upon the five-year-old Magnus Erlingsson, the son of one of their most prominent leaders, the lendmann Erling Skakke, by his wife Kristin, daughter of King Sigurd the Crusader.

To compensate for this shortcoming, Erling and Magnus' party allied themselves with the Church and introduced a new criterion: the king should henceforth be of legitimate birth.

The alliance with the Church, which had recently become better organized in Norway after the establishment of a separate Norwegian archdiocese in Nidaros in 1152, became an important asset for Erling and Magnus.

Sverre had come to Norway from the Faroe Islands and claimed to have recently discovered that he was in fact the son of King Sigurd Munn.

[7] Some materialists among modern historians have tried to read a form of class struggle into Sverre and the Birkebeiner's fight against Erling and Magnus.

Several prominent opponents of Sverre, including Bishop Nikolas Arnesson of Oslo, who was a half-brother of King Inge Crouchback and archbishop Eirik Ivarsson.

Skule was the brother of King Inge and had designs on the throne for himself; however, he contented himself for the time being with leadership of the army, which made him, de facto, the most powerful man of the kingdom.

Discontented elements remained and a revolt in eastern Norway, led by a son of Erling Stonewall called Sigurd Ribbung, dragged on until 1227.

The year 1227 is sometimes considered the end of the civil war era, but most often the term is extended to include the revolt of Skule Bårdsson in 1239–40.

[11] The election of Håkon as king in 1217 seems to have been considered something of a temporary solution until a permanent arrangement could be reached, and Skule undoubtedly hoped that he would soon take over the throne.

At a gathering of the most important men of the kingdom in Bergen in 1223, Skule launched his candidacy to the throne of Norway in opposition to Håkon, along with Sigurd Erlingsson Ribbung and two other pretenders.

Civil wars and internal strife in royal families were common in the Middle Ages, in Norway as in other European countries.

Theodoricus the Monk, who wrote a history of Norway in Latin c. 1180, decided to end with the death of King Sigurd the Crusader in 1130 as he considered it

The contemporary sources, the sagas, strongly emphasise the personal nature of the conflicts—wars arose as a result of the struggle between different people for the possession of the throne.

The unclear succession laws, and the practice of power-sharing between several kings simultaneously, gave personal conflicts the potential to become full-blown wars.

Edvard Bull has also emphasized geographical animosities as a factor, pointing to the fact that different pretenders often found their main support in certain parts of the country.

Also important was the involvement of foreign powers: Danish and, to a lesser extent, Swedish kings were always ready to lend their support to factions in the Norwegian wars, with an eye to extending their own influence, particularly in the Viken (Oslofjord) area.

Knut Helle has emphasised how the Church, after Sverre's death, seemed to work hard to bring about reconciliation between warring parties, and stability.

Its proponents, e.g. Edvard Bull and Andreas Holmsen, sought to explain the civil wars on a social and economic basis.

They assumed that Norwegian society became more stratified in the 12th century, with large groups of previously self-owning farmers sinking to the status of tenant-farmers, while the lendmenn and the Church amassed great landholdings.

These attempts to introduce a form of class struggle-explanation to the conflicts have lost ground more recently, as they seem to have little foundation in the sources.

[19] Ágrip af Noregs konunga sögum also describes the civil war era, but has only been preserved up to the events of c. 1136.

[21] Also, a couple of runic inscriptions written by central figures survive: A rune letter, probably written by King Sverre's son, Sigurd Lavard c. 1200 has been found during excavations in Bergen,[22] and an inscription by Magnus Erlingsson's brother, Sigurd Erlingsson Jarlsson, dated 18 June 1194, has been preserved from a portal of the now dismantled Vinje stave church.