The battle fought on the plains below Uppsala in about 984, in which Eric the Victorious beat and killed his nephew Styrbjörn the Strong and took the byname he is known by. It is the earliest Swedish battle for which any near-contemporary evidence survives — two skaldic stanzas and a pair of Scanian runestones.
Somewhere around 984 an invading army was destroyed on the Fýrisvellir, the flat river meadows that run south from Uppsala along the Fyrisån. The king who destroyed it was Eric, ruler of the Svear from the Uppsala district, and the battle gave him the name by which every later source calls him: Eric the Victorious, Erik Segeräll.
The man he beat was his own nephew. Styrbjörn, called the Strong, was the son of Eric’s brother and co-king Olof, and by the Norse account he had been shut out of his father’s share of the kingdom, gone abroad, married a daughter of Harald Bluetooth and come back with Danish ships to take what he claimed was his.
This is the earliest engagement in Swedish history that can be argued about on evidence rather than legend alone, and the margin is thin. The narrative sources are Icelandic and were written down some two hundred years later. What is older are two stanzas attributed to a poet who fought in the battle, and two runestones raised in Scania for men who, their inscriptions say, did not flee at Uppsala.
The Norse tradition has Eric ruling the Svear jointly with his brother Olof, in the ordinary Scandinavian arrangement in which brothers divided a realm rather than one of them inheriting it whole. When Olof died, his son Styrbjörn was young, and Eric kept the whole kingdom in his own hands.
By the account in Styrbjarnar þáttr Svîakappa and Eyrbyggja saga, Styrbjörn demanded his father’s portion when he came of age, was refused, and left with ships and a following. What he did in exile varies by source: several connect him with the Jomsvikings and with a period as their leader, a tradition that belongs to the semi-legendary Jomsviking material and cannot be pressed.
The Danish connection is the part the sources agree on. Styrbjörn married Thyra, daughter of Harald Bluetooth, and Harald furnished him with a fleet. Harald had his own reason: a Swedish king who owed him his throne would have been a considerable asset on his northern flank, and Harald was in these years building the ring-fortresses and the Jelling monuments of a ruler with ambitions beyond Denmark.
The saga account has Styrbjörn sail into Lake Mälaren and up towards Uppsala, and burn his fleet on landing so that his men would have no way home but through the Swedish army. It is a famous image and a suspect one: burning the boats is a narrative motif that recurs across medieval literature, and a leader whose Danish ships were lent rather than owned had a further reason not to do it.
The route, however, makes sense of the ground. Uppsala stood at the head of navigable water, and an army landing in the Mälaren basin and moving on the cult centre would come up the Fyrisån onto exactly the plains the battle is named for — open, flat and wet, with the river on one flank.
Eric had time to gather the Svear. Later tradition adds that he sacrificed at Uppsala before the fighting and promised himself to Odin after ten years in exchange for victory, a story that presents a pagan king through the eyes of Christian writers who thought they knew what such a bargain cost. It belongs to the memory of the battle, not to its evidence.
Two stanzas attributed to the Icelandic poet Þórvaldr Hjaltason are quoted in later prose as having been spoken at Eric’s court about the battle. If the attribution holds, they are the work of a man who was there, and they are the closest thing to a contemporary report the event has. They celebrate the victory and name the field; they do not describe the fighting.
The runestones are the harder evidence, because they are physical, datable objects that nobody composed to tell this story. The first Hällestad stone in Scania was raised by Áskell for Tóki, son of Gormr, and says that he did not flee at Uppsala; the Sjörup stone, a few kilometres away, says of its man that he did not flee at Uppsala but fought on while he had a weapon.
Neither stone names Styrbjörn, Eric or the Fýrisvellir. What they establish is that in late tenth-century Scania — then Danish — there were men whose families thought a fight at Uppsala was the thing worth carving about, and that some of them did not come back. Scholars have long connected them to this battle, and the connection is strong, but it is an inference rather than a statement on the stone.
No source describes the course of the fighting in a way that can be reconstructed. The sagas say the battle lasted more than one day and that Styrbjörn was killed on the field, and they credit the Swedish victory to Eric’s numbers and to the invaders having nowhere to withdraw.
The consequence is not in doubt. Eric ruled the Svear until about 995 without a recorded challenge, and he is the first Swedish king whose reign leaves a usable historical outline rather than a king-list entry. Adam of Bremen, writing in the 1070s, knows him as a ruler of real weight and records that he attacked Denmark in the 990s — which, if Harald Bluetooth had armed the man who invaded him, is an intelligible piece of retaliation.
The byname is itself the clearest evidence of what the battle meant. A king remembered by his victory, in a tradition that names other rulers for their bloodlines, their tempers or the place they died, was remembered for one thing above all others.
Eric was succeeded about 995 by his son Olof Skötkonung, the first king of both Svear and Götar to be baptised in office, who struck the first Swedish coins at Sigtuna. The house that Eric held together at the Fýrisvellir is the line modern scholarship calls the House of Munsö, and it ruled until the 1060s.
Olof joined Sweyn Forkbeard of Denmark and Earl Eric of Lade in the alliance that trapped and killed Olaf Tryggvason at the sea-battle of Svolder in about 1000 — the next engagement in this part of the north for which any detailed account survives, and one in which the Swedish king appears as a partner of the Danish crown rather than its target.
Uppsala itself remained what it had been. The temple and the assembly there stayed the centre of the Svear’s kingdom for another century, and the struggle over its sacrifices — Inge the Elder was driven out for refusing them around 1080 — shows how much of the world Eric fought in outlasted him.