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.

When King Eric learned that the navy had entered Mälaren, he sent the fiery cross in all directions and amassed the leidang at Uppsala.

The fight lasted all that day and the next without either side gaining the upper hand, even though King Eric had received large reinforcements.

Later that night, a tall man wearing a hat low over his face appeared in his camp and gave Eric a reed; he told him to shoot it over the opposing army and to say Óðinn á yðr alla ("May Odin have you all").

The next day, Eric obeyed Odin's command; the reed appeared to become a javelin as it flew over Styrbjörn's forces, who were all struck blind.

[3] The earlier Odds saga munks praises Sturbiornus and states that King Eric killed two-thirds of the large force arrayed against him and that people credited it to "great power of the devil", because he had promised himself to Oddinus after ten years.

Among his ranks was an Icelandic skald named Þórvaldr Hjaltason, who immediately composed a poem about the victory, for which the king rewarded him with a golden bracelet.

The men, most likely warriors serving King Eric the Victorious, had suffered a violent death in battle close to Uppsala.

Scientists examining the burial speculate that the men died in the battle of Fyrisvellir because the bodies discovered are from the right-time period, the late 900s.

His brother Curt Weibull instead interpreted the runestones and Þórvaldr Hjaltason's verses to indicate that Eric had repelled an invading force of mainly Scanian Vikings led by Tóki Gormsson.

[2] Danish archaeologist Lis Jacobsen dated the runestones to a period after Eric's reign, which would leave the skaldic verses as the only reliable source.