As A History of Ireland in 100 Objects enters a new era, FINTAN O'TOOLEexplains how Norse raiding, trading and settlement affected Ireland from the ninth century

Or, to look at it from the other side, a Norse saga describes the pattern of life of one Svein Asleifarson, a Viking settler on the Orkney Islands: “In the spring, he had more than enough to occupy him, with a great deal of seed to sow . . . Then when the job was done, he would go off plundering in the Hebrides and in Ireland on what he called his ‘spring trip’, then back home just after midsummer where he stayed till . . . the grain was safely in. After that, he would go off raiding again, and never come back till the first month of winter was ended. This he used to call his autumn trip.” One man’s terror was another’s trip.

The explosion of raiders, traders and colonists out of Scandinavia in the eighth and ninth centuries is one of the most extraordinary phenomena in European history. Its influence stretched, at one point or another, to North America and Greenland, south as far as north Africa, Byzantium and Baghdad and as far east as Russia, whose very name derives from the local name for the Swedish traders and colonists, the Rús.

In this, the Russians are not alone. In the forms we now use, the names Ireland, Munster, Leinster and Ulster are of Scandinavian origin. It is arguable that the Vikings transformed Ireland more radically than any other set of invaders. They brought, among other things, cities, money and serious military technology. They posed a profound challenge to Irish society, which had to change profoundly in response.

Why did the Scandinavians suddenly become such aggressive expansionists? Until relatively recently, the favoured explanation was overpopulation and consequent pressure on resources in Denmark, Norway and Sweden. In fact, there’s no evidence that Scandinavia was especially heavily populated in this period: the large-scale clearance of forests to create more arable land in Denmark (an obvious mark of the need for more resources) doesn’t get under way until the 11th century.

The explanation is probably simpler: there was an awful lot of money to be made and the Scandinavians had developed both the technologies and the forms of social organisation to exploit these opportunities. Trade with the thriving Islamic world could bring in enormous wealth: well over 200,000 silver Arabic coins have been recovered from Viking sites. The monasteries of the western isles and then the church and secular centres of the Frankish empire offered equally rich pickings. Fertile lands abroad could be seized by minor nobles, bumping up their status at home.

The Scandinavians were prepared to be flexible, functioning equally well as merchants, colonists, farmers, pirates and raiders. They had both the technological and organisational means to project themselves into distant societies. The longship was a new invention, developed only in the eighth century. It is not accidental that the Vikings began to expand aggressively thereafter: they did it because, now, they could. The longship was one of the great design classics, as flexible as its owners in two distinct ways. The ships had enough give not to be torn apart by strong waves and were able to traverse both the high seas and inland river systems. (It was through the great rivers of Poland and Russia that the Swedes gained access to the Black Sea, Byzantium and the Arab world.) Their weapons, especially the iron swords they adapted from the Franks, were fearsome.

On their own, these technologies would have had limited impact. The Vikings needed systems for passing on information about geography and sources of wealth. They needed the capacity to band together in flexible, often temporary alliances. They needed a culture that balanced a strong individual or family ethic with cults of loyalty, heroism and unity. One Frankish source refers to Viking companies overwintering on the River Seine as sodalities, or brotherhoods. Somehow, the Vikings were able to combine an adventurous, even reckless, spirit with a capacity for co-operation.

THE LATER ROLE of the Scandinavian incomers as traders, craftspeople and city-founders is rightly emphasised in current discussion, but it does not diminish the shock and violence of their initial appearance. Raiding and attacks on monasteries were by no means unfamiliar in indigenous Irish culture, and Irish raiders had terrorised Romano-British communities in the fifth and sixth centuries. But the Danes and Norwegians who descended on Ireland were both rapacious and cruelly destructive. Even sites of little economic value, such as those on the stark Skellig islands, off the Kerry coast, were ravaged. Murder, rape, enslavement and the destruction of saintly relics and holy sites were obviously deeply traumatic.

The first intimations of the coming storm may have spread through contact between monasteries. According to the Anglo-Saxon Chronicle, the great monastery at Lindisfarne, on the Northumbrian coast, was attacked in 793, when “the ravages of heathen men miserably destroyed God’s church . . . with plunder and slaughter”. The Vikings make their appearance in Irish history in 794, when “pagans” are recorded as raiding “all the islands of Britain” (probably meaning those off western Scotland and northern Ireland), including “Rechru”, which is probably Rathlin Island. Four years later, coastal raids by Danes and Norwegians had developed into incursions on to the mainland. In 802 and 806, the paramount monastery of the Irish Christian world, on the island of Iona, off the west coast of Scotland, was attacked. The second raid was so devastating that the monks abandoned Iona and relocated the monastery to Kells, in Co Meath.

By 807, Vikings were even turning up on the west coast, burning Inishmurray, off Sligo, and Roscam, in Galway Bay. By 821, they are recorded as capturing slaves: a large party of Irish women were kidnapped from Howth. And by 840, it could be said that nowhere in Ireland was entirely safe from Viking raids. In 837, two fleets, each of 60 longships, sailed up the rivers Boyne and Liffey, harrying the rich valleys of Cos Meath and Kildare. In 839, raiders sailed up the Lee into Co Cork and also established a base on Lough Neagh.

These incursions were not unopposed, and they were not always successful. One Viking party was routed in Kerry in 812, and in the same year a victory by the Irish over “the Northmen” was considered significant enough to be recorded at the court of Charlemagne, the Frankish emperor. The first named Viking in Ireland, Saxolb, described as “leader of the foreigners”, was killed in battle.

This initial period of hit-and-run raids lasted until roughly 830. It was followed by an ebb and flow of Scandinavian colonisation, in which the Norsemen enjoyed periods of secure control over territory followed by periods of struggle with Irish powers and with other Vikings. Roughly, Viking settlement falls into two phases: the first between the 830s and the 870s, and the second from about 914 to the 940s.

IRELAND WAS ILL-PREPARED for this onslaught. Irish culture in the eighth century was supremely self-confident. It had its own style of Christianity, its own sophisticated legal system, distinctive and highly accomplished art, and a vernacular literature. Its agricultural economy and multitude of petty kingdoms did generate tribal and dynastic conflicts, but they were limited in scale. Indeed, one of the reasons Irish art is so spectacularly opulent in the eighth century is that this was a culture that could afford to put spare resources of wealth and craft into objects of beauty and devotional power rather than military technology and warriors.

The sudden eruption of an aggressive, pagan and initially destructive presence posed a real threat to this self-contained culture. It had to adapt or die. And there was a great deal to adapt to. Military technology had to be upgraded, most obviously by acquiring Viking weaponry. Kings had to develop at least a hard core of semiprofessional warriors. But the Vikings also changed the map of Ireland in ways that had long-term consequences for the natives.

The change can be symbolised by the shift in the centre of gravity from Tara to Dublin. The old Ireland looked, geographically as well as psychologically, inwards. It was the Vikings who developed not just towns but coastal towns: Dublin, Wexford, Cork, Limerick and Waterford. Not all of the Viking towns thrived: large settlements at Linn Duachaill, near Annagassan, in Co Louth, and Woodstown, just west of Waterford, both discovered only recently, lasted for relatively short periods.

There is a paradox here: the Scandinavians were no more an urban people than the Irish. Their own towns arose, in this same period of expansion, as merchant colonies. The founding of Ireland’s coastal cities was, moreover, as much a testament to Viking failures as to their successes. In Iceland, the Faroes and the Scottish islands, the Danish invaders simply occupied land. In northern England, they founded no cities, though they did occupy the old Roman town of York. What made them such prodigious founders of coastal towns in Ireland was the simple fact that they were unable to carve out large swathes of rural territory. They needed their fortified strongholds with quick access to the sea.

Yet, particularly as Irish power began to recover from the initial shock, native kings saw the value of this new way of life. They intermarried with the strangers and sucked them into their own quarrels and alliances. But they also tried increasingly to control and exploit the towns they had created. The Vikings brought with them a more developed commercial culture than Ireland had known: among the words that entered Irish from Old Norse is margad, market. And they gave the country one of the things it came to love more than all else: money.

An exhibition, Raiders, Traders and Innovators – The Vikings and County Louth opens next Friday at the County Museum, Dundalk, Co Louth. A Viking conference will be held at the Town Hall Theatre, Dundalk, on October 22nd and 23rd. dundalkmuseum.ie

A history of Ireland in 100 objects Oseberg ship, circa 815

Very few objects ever did so much to change the course of Irish history as the fearsome and beautiful Viking longship. In the eighth century, Danish and Norwegian shipbuilders developed existing techniques to create a vessel that could both traverse the high seas and navigate the great rivers of Europe. The longship was the spacecraft of its day, propelling adventurers across vast and hitherto unimaginable distances. In one raid in 858, a group sailed from Scandinavia to the coast of Spain, into the Mediterranean, on to Italy, up the River Rhône, raiding all the way, and then back home.

The Vikings didn’t invent the techniques that made possible these light, fast ships, but they did perfect them. The method involved splitting oak trunks with axes, chisels and wedges into long, thin and remarkably flexible planks. These were fixed with iron nails to a single sturdy keel and then to each other, with one plank overlapping the next to create the distinctive “clinker” effect. The low, sleek shape made the ships highly manoeuvrable when steered with a single rudder on the right-hand side of the prow. (This is why the right-hand side of a ship is still known as the starboard – ie steer-board – side.) The ship’s shallow draught meant that it could be rowed far upriver into the heart of the European continent – or, in the case of Ireland, of the island.

Built around 815, in the period when the Viking raids on Ireland began, the Oseberg ship is more than 22m long and 5m wide. Unlike earlier vessels, which had rowlocks on the gunwale, it has 15 pairs of oar ports placed low down so that the oars could strike the water at an efficient angle. Either rowed or sailed (the sail would have covered 90 sq m), it could reach a speed of 10 knots. It is preserved because it was eventually used for the burial of a very high-status woman. The prow and the stern, which rise in beautiful curves 5m above the waterline, have carvings of intertwined beasts, whose quality suggest this may have been a royal vessel. The image on the prow is not the dragon so beloved by film-makers, but a serpent, whose tail is represented by the stern.

It is unlikely that the ships that first raided Irish coasts were anything like as fine as the Oseberg vessel, which in any case would not have been rugged enough for the high seas. But the broad design would have been the same – the one that took Scandinavian raiders and traders as far west as North America and as far east as Kiev.

Yet, even with these masterpieces of functional beauty at their command, the Vikings still had to face into the unknown. Even 600 years after the Oseberg ship was built, an Icelandic navigational manual gives directions to Greenland: “Turn left at the middle of Norway, keep so far north of Shetland that you can only see it if the visibility is very good, and far enough south of the Faroes that the sea appears halfway up the mountain slopes.”

These voyages demanded not just great ships but intrepid sailors.

Where to see it: Museum of Cultural History, Oslo. khm.uio.no