As a supporter of the king, Arnbjørn is reported to have replied: "May be that our lawmen have said this when they had more in them of mead- less than of the laws of Saint Olaf.
"[5] In 1222 Arnbjørn was winning small skirmishes against the Ribbald leaders Herjolf Dint and Eric Ribbon.
[8] In 1225, he had 400 men under his command and was supposed to meet the king at a place called Eidawood but saw the Ribbalds and chased them to Oslo, but they escaped.
[9] The local bishop, who was his foster father and friend, persuaded Arnbjorn to stay to give him counsel despite his wishes to push on to the king.
[15] In 1239, when the king was preparing to go to war with the newly elevated Duke Skule Bårdsson, he sent word to Arnbjørn to raise his levies.