Haakon Sigurdsson ( , ; 937–995), known as Haakon Jarl (Old Norse: Hákon jarl), was the de facto ruler of Norway from about 975 to 995. Sometimes he is styled as Haakon the Powerful (), though the Ágrip and Historia Norwegiæ give the less flattering name Hákon Illi, that is, Haakon the Bad. Background Haakon was the son of Sigurd Haakonsson, Jarl of Lade and ruler of Trøndelag and Hålogaland. His mother was Bergljot Toresdatter, daughter of Tore Ragnvaldsson, Jarl of Møre. Adam of Bremen wrote that he was "of the stock of Ivar (either Ivar the Boneless or Ivar Vidfamne) and descended from a race of giants". In the sagas, Haakon claimed descent from the divine lineage of Sæming, son of Odin. The Hakon Jarl Runestones in Sweden may refer to him. Reign Haakon became jarl after his father was killed by King Harald Greycloak's men in 961. Haakon Jarl warred with King Harald for some time, until he was forced to flee to Denmark, where he conspired with Harald Bluetooth against Harald Greycloak. The two arranged the death of Harald Greycloak around 971, after which Harald Bluetooth invited his foster-son to be invested with new Danish fiefs. Civil war broke out between Haakon Jarl and the surviving brothers of Harald Greycloak, but Haakon proved victorious. After this, Haakon Jarl ruled Norway as a vassal of Harald Bluetooth, but he was in reality an independent ruler. For Harald, he attacked Götaland and killed its ruler Ottar Jarl. Around 973–974, he went to Denmark to help Harald Bluetooth of Denmark in his defense against the Holy Roman Emperor Otto II. Otto's forces successfully opposed an attempt by Harald to throw off the German yoke. After that Haakon paid no taxes to Denmark. In 980 he assisted his Ruthenian cousin Vladimir the Great in reclaiming Novgorod from Yaropolk I of Kiev. Haakon was a strong believer in the old Norse gods, even after Harald Bluetooth forced him to accept baptism around 975 and assigned him clergymen to take to Norway to spread Christianity. When a favourable wind came for Haakon to leave, he commanded the clergymen to return ashore, and broke his allegiance to Denmark. In 977 Vladimir I of Kiev fled to him, collecting as many of the Viking warriors as he could to assist him to recover Novgorod, and on his return the next year marched against Yaropolk I