King Askild And Grjötgard

King Tryggve was the one responsible for everything but what really happened?

The Kingdom of Ranrike that Tryggve led made contact with the Kingdom of Orkdalen led by Gryting. 

King Gryting initially had no interest in attacking Rogaland because he had nothing to gain from it but he was not the sharpest tool in the shed either. 

Tryggve was a cunning man and it took a little convincing but he promised King Gryting wealth beyond his comprehension and that was enough to convince the King of a struggling Kingdom to partake in this attack.

King Tryggve already ensured a fail-safe plan and that was what he did in Iceland, he was aware of the Gardssons' presence there and knew that they were watching. 

That was why he did what he did with his arm, this would further give credibility should he result to this.