The backdrop of the battle was the unification of Norway into a single independent state after longstanding Danish efforts to control the country, combined with the spread of Christianity in Scandinavia.

As the battle starts Olaf is shown dismissing the Danish and Swedish fleets with ethnic insults and bravado while admitting that Eirik Hákonarson and his men are dangerous because "they are Norwegians like us".

In earliest recorded history, Norway was divided into a number of small and sometimes warring petty kingdoms with weak central authority.

In traditional historiography the rise of Harald Fairhair in the ninth century started the process of unification of the country and the consolidation of royal power.

[4] In the 970s, Haakon Sigurdsson, Jarl of Lade, became the most powerful man in Norway, at first supported by Harald Bluetooth of Denmark and paying tribute to him—though the two later fell out over religious matters.

While rejecting Danish authority, Olaf made it his mission to convert Norway and the Norse colonies in the west as quickly and as completely as possible.

Proceeding with threats, torture and executions, Olaf broke down pagan resistance and within a few years Norway was, at least nominally, a Christian country.

Working from skaldic poetry, oral history, learned European examples and an uninhibited imagination, Oddr constructed an elaborate account of the battle.

Contemporary skaldic poetry which refers to the battle includes a work by Hallfreðr the Troublesome Poet, who was in Olaf Tryggvason's service.

[8] While historians value contemporary skaldic poetry highly as the most accurate source available, it must be remembered that the poems are not preserved independently but as quotations in the kings' sagas.

Angered, Olaf launched an expedition to attack Denmark, but he was too impatient to wait for a fleet to assemble from all of Norway, and he set sail for the south with only 11 ships, expecting the rest to follow.

While it is possible that Olaf was collecting dowry, it seems more probable that he was expecting war and seeking allies in Wendland, but met with little success.

The sagas explain the discrepancy by saying that some of the 71 ships belonged to Jarl Sigvaldi, who deserted Olaf, and that others sailed past the trap at Svolder before it was sprung.

According to Fagrskinna it was "the biggest of all ships",[35] but Heimskringla gives more detail: Original Icelandic text: Eiríkr jarl hafði barða einn geysimikinn, er hann var vanr at hafa í víking;þar var skegg á ofanverðu barðinu hváru tveggja;en niðr frá járnspǫng þykk ok svá breið sem barðit ok tók alt í sjá ofan.Open translation: "Earl Eirik owned a mighty great ship (referred to as a barda) which he was accustomed to take on his viking expeditions;it had iron plating (referred to as beard) lining the outward strakes in both directions;beneath it, an iron beam (a ram) protruded, thick and wide as the stem, which took all at sea above.

Olaf Tryggvason's ships pass the anchorage of his allied enemies in a long column without order, as no attack is expected.

As progressively larger vessels appear, the Danes and Swedes think each one is the Long Serpent and want to attack straight away, but Eirik holds them off with informed comments:[41] It is not King Olaf on this ship.

It is manned with such fellows that, should we encounter King Olaf Tryggvason, we will quickly learn that it would be better for us to find a gap in his fleet than to do battle with this longship.

Eirik makes a remark "so that few men heard him" saying that "with only the Danish army at his disposal, King Sveinn would never command this ship".

After spotting the enemy, Olaf might have used sail and oar to outrun the ambush and escape, but he refuses to flee and turns to give battle with the eleven ships immediately about him.

The advantages of this arrangement were that it left all hands free to fight, that a barrier could be formed with the oars and yards, and that it limited the enemy's ability to make its superior numbers count.

The Long Serpent was the longest ship and so also the tallest—another advantage to the defenders, who could rain down arrows, javelins and other missiles while the enemy would have to shoot upwards.

[40] The sagas give all the credit to the Norwegians, praising Eirik Hákonarson for any intelligence and for most of the valour shown by Olaf Tryggvason's opponents.

The Danish sources report that when all was lost he committed suicide by throwing himself into the sea, "the end befitting his life", according to Adam of Bremen.

[49] Saxo Grammaticus says that Olaf preferred suicide to death at the hands of the enemy and jumped overboard in full armour rather than see his foes victorious.

[53] King Olaf, like Charlemagne, Frederick Barbarossa and Sebastian of Portugal, is one of those legendary heroic figures whose return was looked for by the people, their deaths never completely accepted.

The battle was very famous too, on account of the great slaughter, and the Earl's success in clearing a ship that up to that time was the largest built and the fairest in Norway; of which shipmen said that it would never, while floating on the sea, be won with arms in the face of such heroes as manned it.

[60] With the 19th century rise of nationalism and romanticism and the growing number of translations of the sagas, interest in the battle of Svolder increased outside of Iceland.

Around 1830, the Faroese poet Jens Christian Djurhuus composed a ballad on the battle titled Ormurin langi, following Snorri's account.

In Norway, Johan Nordahl Brun's rousing patriotic play Einar Tambarskjelve, written in 1772, is considered a milestone in Norwegian literature.

[65] The best known English-language work is probably Henry Wadsworth Longfellow's cycle "The Saga of King Olaf" (from his 1863 collection of poems Tales of a Wayside Inn), much of which is dedicated to the Battle of Svolder, and which includes the verse:[66]