Battle of Fýrisvellir The Battle of Fýrisvellir was a battle for the throne of Sweden which was fought in the 980s on the plain called Fýrisvellir , where modern Uppsala is situated , by King Eric the Victorious and his nephew Styrbjörn the Strong . It is mentioned in a number of medieval sources , such as " Eyrbyggja saga " , " Knýtlinga saga " , " Hervarar saga " and Saxo Grammaticus ' " Gesta Danorum " ( Book 10 ) , but the most detailed account is found in the short story " Styrbjarnar þáttr Svíakappa " . Prelude . Styrbjörn had made himself the ruler of the Jomsviking s but wanted to amass an even greater force in order to take the crown of Sweden , which the Swedish Thing had denied him on his father ' s death , a death of poisoning of which he suspected his uncle Eric . Styrbjörn ' s method was to pillage far and wide in the newly created kingdom of Denmark until its king Harald Bluetooth asked for a settlement . Harald gave Styrbjörn his daughter Tyra as his wife and Styrbjörn went away , but he then returned to Denmark with 1000 longship s . He forced the Danes to give him 200 ships and whoever among them he saw fit to take with him , including the king himself . He then set sail for Sweden with his armada of longships . Battle . When Eric the Victorious learnt that the navy had entered Mälaren , he sent the fiery cross in all directions and amassed the " leidang " at Uppsala . Þorgnýr the Lawspeaker , a friend of Eric , advised him to put stakes in the waterway which led to Uppsala . When Styrbjörn ' s navy arrived and saw that they could not sail further , Styrbjörn vowed never to leave Sweden , but to win or die . In order to encourage his men to fight to the death , he set the ships on fire . King Harald Bluetooth , however , did not want to take part in this and left with the Danish navy . Styrbjörn swallowed his pride at this treachery and marched towards Uppsala with the Jomsvikings . When the Swedes wanted to stop their advance in the forest , Styrbjörn threatened to start a forest fire , and this convinced the Swedes to let Styrbjörn and his men pass through the forest without harm . Þorgnýr told king Eric to tie together cattle and harness them with spears and swords . When the enemy approached on the Fýrisvellir , thrall s pushed the herd towards the Jomsvikings , which caused havoc among their ranks . However , Styrbjörn was an excellent warchief and restored order in his ranks . The fight lasted all day and in the evening there was a stalemate . The next day also ended in stalemate , even though King Eric had received large reinforcements . During the night , Styrbjörn sacrificed to Thor , but the red - bearded god showed himself angry and foretold a great defeat . Eric , on the other hand , went to the Temple at Uppsala and sacrificed to Odin , promising himself to him after ten years . A tall man in a blue cloak and a broad - brimmed hat showed himself to Eric . It was Odin , who gave Eric a cane and told him to throw it over the Jomsvikings and to say " I give all of you to Odin " . The third day , Eric obeyed Odin ' s command and a hail of arrows fell over the Jomsvikings , a hail that the men called " Odin ' s arrows " . When Styrbjörn understood that it was all over , he screamed to his men to stand and fight , thrust his banner into the soil and rushed into the Swedish army with his best champions . Few men fled that day . Aftermath . After the victory , King Eric mounted one of the royal mounds and promised a great reward to whoever who could compose a poem about the victory . Among his ranks was an Icelandic skald named Þórvaldr Hjaltason , who immediately composed a skaldic poem about the victory , for which the king rewarded him with a golden bracelet . As a result of this battle , King Eric became known as " the Victorious " . Mentions on runestones . Runestone s are counted as historic documents about the events of the Viking Age in Scandinavia . The following four runestones mentions people who may have died in the battle . Note that the first runestone mentions a warleader named Tóki Gormsson and he may have been a son of the Danish king Gorm the Old , an interpretation which fits the fact that Styrbjörn was allied with another son of Gorm , Harald Bluetooth .