Sverre’s old adversaries, the bagler, were exploiting the situation to launch a new invasion of Viken under their king, Erling Steinvegg.

After the infant king Guttorm’s death in August 1204, the birkebeiner needed a strong leader to oppose the bagler threat.

The birkebeiner leaders wanted earl Haakon the Crazy, who had earlier been appointed to rule the kingdom in king Guttorm’s infancy.

A compromise was reached, whereby Inge became king, while earl Haakon became leader of the army, and received half the royal income.

The next year, the 'birkebeiner' launched a successful attack on the 'bagler' stronghold of Tønsberg, but the war dragged on with neither side able to gain a decisive victory.

In autumn of 1207, archbishop Tore of Nidaros and bishop Nikolas of Oslo, a prominent 'bagler', started negotiations for a settlement of the dispute.

They succeeded in bringing about a meeting between kings Inge, Philip, and earl Haakon, at Kvitsøy in Rogaland in the autumn of 1208.

He was to remain in control of eastern Norway with Viken, except Bohuslän, with the title of earl under king Inge.

He never achieved control over all of Norway, and agreed to a power-sharing with the bagler, which he stuck to even though Philip broke the agreement by continuing to style himself as "king".

As a reaction to such views, others have claimed that Inge was a strong ruler, in that he was able to withstand the pressure of the more war-like among the birkebeiner and put a halt to the destructive civil wars for a time.

The bagler sagas - a contemporary source - describes Inge as a quiet and calm man, who shied away from feasting and preferred to spend his time in his own quarters with close friends - a character trait which was held against him by some of his men.