The contrast is great to the traditional Norse warrior ideals where the king was expected to lead his men from the front of the battle line.

If Sverre was 30 years old when he became a priest, this would place his birth no later than 1145, making his paternal claim impossible, as Sigurd Munn was born in 1133.

However, other objections remain, such as the fact that Sverre consistently refused to undergo an ordeal by fire to prove his claims.

At the time, such a trial was routine for new claimants to the throne, and belief in its efficacy seems to have been universal; yet Sverre refused to undergo it.

Sverre's actions offered her a welcome possibility to divorce from the marriage with Folkvid the Lawspeaker, into which she claimed to have been forced by Erling Skakke.

Erling Skakke had been regent during his son's minority and continued to be the country's real ruler even after Magnus had come of age.

There he met with the local ruler, Birger Brosa, who was married to Sigurd Munn's sister, Brigit Haraldsdotter.

Upon Sverre's initial contact, the Birkebeiners had been reduced to a ragtag army of brigands and vagabonds with no more than 70 men, according to the saga.

After fleeing south, they met Magnus' army in Ringerike, with the skirmish ending in a tactical victory for the Birkebeiners.

With Magnus out of the country, Sverre could sail south and occupy Bergen, but his hold on the region remained weak.

During summer 1182, Magnus made an attempt to take Nidaros by siege, but was repulsed with grave losses when the Birkebeiners launched a surprise night attack.

In the sea battles of medieval Scandinavia, the side with the largest and highest ships would usually have an advantage, since this meant the crew could attack the enemy from above with projectiles and other weapons.

Now that the dissatisfied priest and his band of vagrants and outcasts had become king and rulers of Norway, Sverre worked to consolidate his power.

Sverre himself married the Swedish princess Margaret, daughter of Erik the Saint and sister of King Knut Eriksson of Sweden.

Eirik on his side preached against the king and his men, and sent letters of complaint to the Pope, but in the short term his offensive weapons were few.

In 1190 Sverre attempted to force the archbishop into submission, claiming that Eirik had broken the law by having 90 armed men in his service.

In a letter dated 15 June 1194, Pope Celestine III laid out the foundational rights of the Norwegian Church supporting Eirik on every point.

[9] Empowered by this letter, Eirik could take the step of excommunicating Sverre and order the Norwegian bishops to join him in exile in Denmark.

In October, Innocent III placed Norway under interdict and in letters to Eirik accused Sverre of forgery.

They did the contrary: Sweden continued actively to support the Birkebeiners and John of England sent mercenaries to help Sverre.

By referring to well known theological works such as the Decretum Gratiani and the writings of Augustine of Hippo, the author attempted to prove that the excommunication of Sverre was unjust and thus not binding.

By now Sverre had his hands full with the church-supported Bagler rising, and the direct struggle with the church became a sideshow, at least for him personally.

Their leaders were Nikolas Arnesson, the nobleman Reidar Sendemann from Viken and Sigurd Jarlsson, a bastard son of Erling Skakke.

The Baglers had Inge hailed as king on Borgarting and soon established a firm control over the Viken region, with Oslo as their main seat.

In spring 1197, Sverre called out the leidang from the northern and western parts of the country, and in May he was able to sail south to Viken with more than 7000 men, a considerable force.

The garrison at Sverresborg held fast for a while until their commander Torstein Kugad changed sides and let the Baglers into the castle.

Sverre could now take control over Viken and prepared to spend the winter in Oslo, but the countryside remained largely hostile.

Early the next year, a spontaneous uprising took place as huge numbers of people started drifting towards Oslo to throw the Birkebeiners out.

The siege dragged on because the other Bagler leaders dared not send a relief force and the garrison did not fall for any of Sverre's tricks.

On his death bed, Sverre appointed his sole living son, Håkon, as his heir and successor and in a letter advised him to seek reconciliation with the Church.