Haakon's foster-father Tore Tordsson ("Steigar-Tore"), who refuses to recognize Magnus as king after Haakon's death had been the strongman behind the monarch.

With Egil Aslaksson and other noblemen, he has the otherwise-unknown Sweyn Haraldsson set up as a pretender.

Although later sagas maintain that Sweyn was Danish, some modern historians have speculated that he may have been a son of Harald Hardrada.

The revolt is based in the Uplands, but also gains support from noblemen elsewhere in the country.

After several weeks of fighting, Magnus captures Tore and his supporters and has them hanged on the island of Vambarholm (outside Hamnøy, Lofoten, in northern Norway).

Magnus was reportedly furious because he could not pardon Egil, a potentially useful, young and resourceful nobleman.

As king, his honor would only allow a pardon if other noblemen pleaded for Egil's life; this did not happen.