By the turn of the second millennium, Norway had been a unified kingdom for about two centuries. But how united was this northern realm?

In 871, though Harald Fairhair had united the petty kingdoms that had emerged in Norway during the early medieval period under his rule, there were still powerful forces within Norway that dominated vast regions of the country.

In the north, the powerful Jarls of Lade controlled the lucrative "Northern Way" trade route and used this economic base to fuel their political ambitions.

In the south, especially around what is now Oslo, it was the rulers (and later kings) of Denmark who exerted their influence and authority through Norwegian vassals. 

A century after Norwegian unification, a powerful Jarl of Lade, Haakon Sigurdsson, became a de-facto ruler of Norway with the support of the Danish king, Harald Bluetooth. 

However, this proved to be a political marriage made in hell. 

While Harald had converted to Christianity, Haakon Sigurdsson still adhered to the Old Norse religion. Bluetooth soon ousted Haakon and installed a new Christian king, Olaf Trygvasson, on the Norwegian throne. 

Tryggvason's reign was not a peaceful one. 

He saw it as his divine mission to convert all in his kingdom to Christianity and often did so with the point of a sword. 

Within the first 4-5 years of his reign, starting in 995, King Olaf I had overcome pagan resistance, destroyed temples and sacred groves, and – to put it bluntly – angered many in his kingdom. 

The sons of the King of Denmark, Sweyn Forkbeard, and the Jarl of Lade, Eirik Jarl, soon began scheming to claim what they believed was their birthright. 

A trap is set 

Sadly, like all good Viking battles, we have scant historical records. 

What little detail we have either comes from skaldic poetry and chronicles compiled, at a minimum, decades later. 

In 1080, the medieval German historian Adam of Bremen wrote the most detailed account of the battle nearly a century after the fact. 

Accounts vary regarding the exact cause of the naval battle. 

While the quest for the Norwegian throne by Olaf's rivals is a known factor, some spicier details have emerged. 

Olaf's Danish wife is said to have encouraged him to wage war against her native land. Additionally, there were rumors of an unpaid dowry to Forkbeard, as Olaf's wife was allegedly Forkbeard's sister.

Whilst all accounts agree that war was to be waged, reports conflict about the events leading up to the engagement. 

Some accounts argue that Olaf was so keen to wage war on Denmark that he sailed with only 11 ships, with the rest still preparing for war. 

When the rest of his fleet did not make speed, Olaf sailed to the Wendish shores near Jomsborg, seeking allies. 

It was here he faced an ambush. 

One historical account, penned in Iceland during the 12th century, sheds more light on this event. It describes how Sweyn Forkbeard and Eirik Jarl schemed to ensnare Olaf. 

When Olaf went to Wendland to collect part of his dowry, he was warned about a potential ambush. 

Despite this, the local ruler – secretly collaborating with Forkbeard and the Jarl of Lade – downplayed these rumors. 

Feeling secure, Olaf decided to send the majority of his fleet back to Norway, choosing to return later with only a small force of 11 ships. 

This decision proved perilous, as he was ambushed during his journey home. 

The prowess of Viking shipbuilding was on full display during the Battle of Svolder, where the fate of nations was decided upon the waves. Photo: BTBScanpix / Wikimedia Commons (CC BY-SA 4.0)

The Long Serpent and overwhelming odds 

All accounts concur that the battle occurred in early September of either 999 or 1000.

The year's discrepancy can be attributed to the medieval calendar system, which, thankfully, we have since refined and improved.

What these sources also unanimously report is that King Olaf had a minuscule force of just 11 ships.

In contrast, the forces of Forkbeard and the Jarl of Lade reportedly commanded an armada ranging from 80 to 139 ships.

Even using the conservative estimate of 80 ships, this force was almost eight times larger. Clearly, the odds were overwhelmingly against the Norwegian king. 

However, what King Olaf did possess – if the sagas and poems written about the naval battle are to be believed – was one of the best Viking ships ever built. 

This flagship, known as the Ormrinn langi (Old Norse for "The Long Serpent"), had a crew of over 68 rowers and was said to measure approximately 48 meters (150 feet) in length. 

Olaf confiscated the ship from a pagan ruler who had declined to convert to Christianity. 

The former owner of The Long Serpent met a grim fate at Olaf's hands with a red-hot iron after blaspheming Jesus' name in the presence of the Norwegian king. 

Somewhere in the Øresund, the body of water dividing the Swedish and Danish coasts, Olaf and his ships sailed right into a trap. 

However, Olaf's enemies were reluctant to attack until they had sighted The Long Serpent. 

Realizing the trap, the Norwegian king assembled his ships in a defensive line, with his largest ship, The Long Serpent, at the center.

The battle had begun! 

High drama on the high seas 

Although vastly outnumbered, the battle appears to have been, to borrow from the Duke of Wellington, "a damned close-run thing."

The sagas relate a bloody and epic battle that ebbed and flowed.

The enemies of Olaf charged his defensive line repeatedly but at a great cost to both men and ships.

However, to borrow another phrase from a famous leader, Joseph Stalin, "quantity has a quality all its own," and soon the Norwegian king's ships were picked off one by one until only The Long Serpent remained afloat.

During this time, however, the Norwegian forces almost succeeded in killing the Jarl of Lade with a crossbow, but, according to the sagas, the arrow narrowly missed the would-be king. 

Both the historical chronicles and the sagas regale us with tales of King Olaf's bravery and defiance.

When all hope was lost, some accounts claim King Olaf jumped into the ocean in full armor, choosing to end his life rather than fall into enemy hands. 

Other accounts suggest the King went down with his ship, vanishing into the darkness below. 

Following the Battle of Svolder, Norway's territories were divided among Eirik Håkonsson, Svein Håkonsson, and areas directly under Svein Forkbeard. Source: Tokle, NordNordWest, Mclean / Wikimedia Commons (CC BY-SA 4.0)

A mythical legacy 

However gloriously King Olaf was said to have fought and died, the battle was ultimately won by his enemies. 

The victors swiftly divided his kingdom: part of central and northern Norway went to a Swedish ally; the Jarls of Lade solidified their hold on northern Norway; and the Viken district, around what is now Oslo, came directly under the Danish crown. 

The remainder of Norway was also placed under the vassalage of the Danish crown. 

It appears that these new rulers had a light touch. 

This allowed a degree of religious freedom and harmony in which many subjects reverted to their old religious beliefs, undoing some of the work that Tryggvason had done to Christianize his kingdom. 

The battle is remembered today not only for its epic bloodiness – with hundreds if not thousands, said to have been slaughtered – but also for the dramatic end of King Olaf. 

Much like other legendary medieval kings (real or imagined), such as King Arthur, Frederik Barbarossa, Charlemagne, or even Constantine XI Palaiologos, King Olaf Trygvasson became one of those fabled figures. 

His death was never fully accepted, and a mythical return was anticipated by his future subjects. 

For more information on what made Vikings so successful in warfare, even against their own, read an article by Science Nordic here

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