According to the "Heimskringla", the Battle of Soknasund occurred during 1033 in Ryfylke. Tryggve the Pretender came with an army from England. He said he was the son of Olav Tryggvason and therefore claimed the kingdom as his own. When word reached Sveinn Alfífuson and Aelgifu that Tryggve's invasion was imminent, they summoned the landholders of Halogaland and the Trondheim district to join the royal army in resisting Tryggve. Svein Knutsson and his army, probably including elite Danish troops stood against them. Sveinn and his forces made their way south to Agder, believing that Tryggve would attempt to slip through the Skagerrak and join his supporters in Viken. Tryggve, however, landed instead in Hordaland, then sailed to Rogaland to attack Sveinn's navy. The two fleets met off the island of Bokn. Svein won the Battle of Soknasund and Tryggve Olavsson was killed.