986 - Sweyn Forkbeard became king

Denmark
Sweyn Forkbeard broke with his father Harald Bluetooth, this might be because of the relative peaceful regime of Harald Bluetooth. A new young group had heard a lot of stories about audacious viking raids and lusted for adventure. The young group gathered around Sweyn Forkbeard, who had the hird (Royal guard) on his side.
Sweyn Forkbeard

The viking mercenaries the Jomsvikings on the Eastern coast remained loyal to Harald Bluetooth. Sweyn Forkbeard won the battle at Helnaes, near Assens and Harald Bluetooth became deadly wounded, his men took him to Jomsborg where he died, his corpse was taken to the church which he built himself: The holy trinity church at Roskilde where he was buried.
Sweyn Forkbeard was now king, he ruled until 1014.
Norway
Håkon Sigurdsson of Norway defeated the Danish invasion force at the Battle of Hjörungavágr.