Danelaw
The Vikings arrived in force in East Anglia in 866, and in 870 they killed the East Anglian king, Edmund. However, it was not until after the Treaty of Wedmore in 878, agreed between Alfred the Great of Wessex and Guthrum of Denmark, that Viking settlement of East Anglia began in earnest. As the Anglo-Saxon Chronicle put it, Guthrum's Viking army proceeded to `share out' the land, which remained part of the Danelaw for the next 40 years. Only five major place-names in Suffolk of purely Danish origin contrast with a few dozen in Norfolk. With its rich soils and kind climate East Anglia had carried a large rural population in Roman times. By the middle of the 9th century settlement had been established all over East Anglia in almost all the land units which were later to become parishes. By the early years of the 10th century two more large towns had emerged, Norwich in Norfolk and Thetford on the border between the two shires. Elsewhere in the Danelaw, other towns were developing in similar fashion, for example the `five boroughs' of Lincoln, Stamford, Leicester, Nottingham and Derby. Viking towns were soon established at Dublin, Waterford, Wicklow, Cork and Limerick.
Alfred had to concede the northern and eastern counties to the Vikings, where their disbanded armies settled, created new settlements and merged with the local populations. Lincoln, Nottingham, Derby, Stamford and Leicester became important Viking towns within The Danelaw (or 'Scandinavian England'), while York became the capital of the Viking Kingdom of York which extended more or less over what we call Yorkshire.
In 917, the Vikings re-captured the settlement of Dubhlinn [Dublin] which the Irish had captured in 902. The king of the Uí Néill, Niall Glúndub, who was the most powerful king in Ireland, decided that the Vikings had to be stopped. He brought together a combined force from the Uí Néill and enlisted the help of the forces of Leinster. They marched against the Vikings in Munster in 917. The Vikings continued to raid inland from their towns of Dubhlinn, Cork and Vadrefjord. In 921, they founded a new town on the south-east tip of Ireland called Weisfjord (Wexford) and a yeare later founded the town of Limerick near a ford at the mouth of the river Shannon on the west coast.
By 950, the Vikings had stopped raiding in Ireland and developed instead as traders and settled in the lands around their towns. In France, the Vikings formed the Kingdom of Normandy on the north coast - which would play a major role in history a century later when William of Normandy would defeat England in 1066. The Vikings left many placenames in Ireland including: Dublin, Cork, Limerick, Waterford, Wexford, Strangford, Leixlip, Carlingford, Youghal, Howth, Dalkey and Fingall [an area of modern-day Dublin].
Unlike Britain and France, where whole monastic communities disappeared, the Irish seem to have been spared the worst of the Vikings' wrath. Cork monastery was practically next door to the nearby Viking settlement but it emerged from the Viking period largely intact. Thus both ringforts and crannogs fell out of use over the course of the 900s. They were replaced by a more heavily defended underground chamber called a souterrain. A souterrain is built by digging a deep ditch, lining it with stone walls, putting a roof on it and covering it over. At the start of the Viking period the Irish monasteries consisted of earthen enclosures containing a church, various outbuildings and the monks' residences. The Vikings found that it was very easy to ransack these largely defenseless settlements. In time, the monks learned how to frustrate the Vikings, by building tall stone towers known as Round Towers.
Ireland in the 10th century had been dominated by the power of the Uí Néill. In the mid 900s, the power of the dominant royal family in Munster, the Eóganacht, was being sapped by attacks from the Uí Néill. This allowed the Dál Cais who resided in the Shannon basin area of north Munster, to increase their dominance in the province. They were helped by the fact that the Shannon river was growing in importance with Viking trade. In 976 Mathgamain, Lord of the Dál Cais, was assassinated by the Vikings of Limerick. The Vikings, who had converted to Christianity, ruled a territory around this settlement at the mouth of the Shannon. When Mathgamain's brother, Brian Bóruma (Brian Boru) succeeded him to become Lord of the Dál Cais, he wasted little time.
Brian Boru's first action was to attack the Vikings of Limerick. King Ímar of Limerick and his sons took refuge in the monastery of Scattery Island, but Brian Boru must have decided that he did not much care for sacred traditions. He broke into the sanctuary, slaughtered the Vikings and desecrated the church. Although only founded 50 years earlier, Limerick would remain in Munster's hands for the next two centuries. By 980 he had surpassed the Eóganacht and crowned himself King of Munster. Thirsty for more power, Brian Boru next formed a strategic alliance with the Vikings of Vadrefjord (Waterford) to penetrate his armies deep into Connacht and the relatively weak province of Leinster (Laigin) in the 980s. Meanwhile, the Uí Néill became increasingly alarmed at the rise and rise of King Brian Boru of Munster and sought to limit his growth. During the 980s, King Máel Sechnaill 2nd of the Uí Néill tried various tactics, but by 997 came to the conclusion that he could not be lord over Boru. Therefore the two Kings held a meeting at Clonfert, within the Viking Kingdom of Dubhlinn and agreed to divide Ireland between them. Máel Sechnaill II granted Brian Boru effective High Kingship over Munster, Leinster and Dubhlinn and retained the allegiance of Connaught and his own province for himself.
However, not everyone accepted the arrangement. In 999, the Lords of Leinster and the Viking King of Dubhlinn revolted against his rule. Undeterred, Boru marched his armies back into Leinster and defeated them heavily at Glenn Máma. Descending on Dubhlinn at the height of winter, he attacked it, plundered the city and burned down its fortress. Eventually King Silkenbeard of Dubhlinn submitted to Brian Boru and, in the coming decade, was his supporter. In 1002, Máel Sechnaill II himself finally submitted to Boru. After this, Brian Boru set out to assert his control over the whole island. He made two circuits of the island in 1005 and 1006 when he penetrated the furthest reaches of the Kingdom of the Uí Néill.