The siege of Dumbarton was a successful four-month siege of the Brittonic fortress at

Dumbarton Rock Dumbarton (; , or ; or , meaning 'fort of the Britons') is a town in West Dunbartonshire, Scotland, on the north bank of the River Clyde where the River Leven flows into the Clyde estuary. In 2006, it had an estimated population of 19,99 ...

in 870, initiated by the

Viking Vikings were seafaring people originally from Scandinavia (present-day Denmark, Norway, and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded, and settled throughout parts of Europe.Roesdahl, pp. 9� ...

leaders

Amlaíb Olaf or Olav (, , or British ; ) is a Dutch, Polish, Scandinavian and German given name. It is presumably of Proto-Norse origin, reconstructed as ''*Anu-laibaz'', from ''anu'' "ancestor, grand-father" and ''laibaz'' "heirloom, descendant". Old Eng ...

King of Dublin The Kingdom of Dublin (Old Norse: ''Dyflin'') was a Norse kingdom in Ireland that lasted from roughly 853 AD to 1170 AD. It was the first and longest-lasting Norse kingdom in Ireland, founded by Vikings who invaded the territory around Dublin ...

, and

Ímar Ímar ( ; died c. 873) was a powerful Viking leader in Ireland and Scotland in the mid-late ninth century. He was the progenitor of the Uí Ímair dynasty, who would go on to dominate the Irish Sea region for several centuries. He was the son o ...

. Dumbarton was capital of the Kingdom of Alt Clut, the only surviving Brittonic kingdom outside of

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

. It represented a valuable target for the Viking invaders, who were likely motivated by strategic considerations, as well as loot. The attackers may have wished to remove Alt Clut as a maritime power, and the location and defensiveness of Dumbarton itself was of major value. The siege lasted four-months, a length of time unprecedented in the history of Viking warfare in the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

, and ended when the defenders ran out of water. After the siege numerous prisoners were taken and sold into slavery in Dublin. Following this defeat, the power centre of Alt Clut moved to the vicinity of

Govan Govan ( ; Cumbric: ''Gwovan''; Scots language, Scots: ''Gouan''; Scottish Gaelic: ''Baile a' Ghobhainn'') is a district, parish, and former burgh now part of southwest Glasgow, Scotland. It is situated west of Glasgow city centre, on the sout ...

, and it became known as the

Kingdom of Strathclyde Strathclyde (, "valley of the River Clyde, Clyde"), also known as Cumbria, was a Celtic Britons, Brittonic kingdom in northern Britain during the Scotland in the Middle Ages, Middle Ages. It comprised parts of what is now southern Scotland an ...

. The loss of Dumbarton caused the kingdom to increasingly fall under the influence of the Scottish

Kingdom of Alba The Kingdom of Alba (; ) was the Kingdom of Scotland between the deaths of Donald II in 900 and of Alexander III in 1286. The latter's death led indirectly to an invasion of Scotland by Edward I of England in 1296 and the First War of Scotti ...

Background

Following the

Anglo-Saxon invasion of Britain The settlement of Great Britain by Germanic peoples from continental Europe led to the development of an Anglo-Saxons, Anglo-Saxon cultural identity and a shared Germanic language—Old English—whose closest known relative is Old Frisian, s ...

, the Kingdom of Alt Clut was the only remaining Brittonic kingdom outside of Wales. At the time of the siege it was ruled by

Arthgal ap Dyfnwal Arthgal ap Dyfnwal (died 872) was a ninth-century king of Alt Clut. He descended from a long line of rulers of the British Kingdom of Alt Clut. Either he or his father, Dumnagual IV of Alt Clut, Dyfnwal ap Rhydderch, King of Alt Clut, may have r ...

. For most of the 9th century, Alt Clut had escaped the worst of the

Viking invasions of Scotland Scandinavian Scotland was the period from the 8th to the 15th centuries during which Vikings and Norse settlers, mainly Norwegians and to a lesser extent other Scandinavians, and their descendants colonised parts of what is now the periphery of ...

. By 870, the settlement on

was the centre of a small but wealthy kingdom. The site was strategically important, commanding the confluence of the rivers Clyde and Leven. Conquering Dumbarton would make it possible for the Vikings to sail upriver into the central lowlands of Scotland. Dumbarton Rock was an extremely strong defensive position and had previously survived several sieges, including a co-ordinated assault by

Angles Angles most commonly refers to: *Angles (tribe), a Germanic-speaking people that took their name from the Angeln cultural region in Germany *Angle, a geometric figure formed by two rays meeting at a common point Angles may also refer to: Places ...

and

Picts The Picts were a group of peoples in what is now Scotland north of the Firth of Forth, in the Scotland in the early Middle Ages, Early Middle Ages. Where they lived and details of their culture can be gleaned from early medieval texts and Pic ...

in 756. Following his successful invasion of England, including the conquest of

York York is a cathedral city in North Yorkshire, England, with Roman Britain, Roman origins, sited at the confluence of the rivers River Ouse, Yorkshire, Ouse and River Foss, Foss. It has many historic buildings and other structures, such as a Yor ...

in 866,

joined forces with

, the Scandinavian

, to target this prosperous town. Aside from loot, possible objectives might have included neutralising the Britons as a maritime power. No other campaign by Ímar and Amlaíb involved such a concentrated assault in one place, providing evidence of Alt Clut's continuing power at the time.

Siege

In 870 Amlaíb and Ímar gathered their combined forces and launched their attack on Dumbarton. Unable to take the fortress, they besieged the rock for a period of four months, a length of time highly unusual for the period, and unprecedented in the history of

warfare in the British Isles. The defenders survived four months of the siege before the well ran dry, forcing them to capitulate. Accounts of the siege in Welsh chronicles describe the destruction of the summit of Dumbarton Rock. Based on these texts, historian Alan Macquarrie suggests that after a prolonged siege the Norse attackers may have seized the lower part of the rock, where the well was located, forcing the defenders to retreat to the highest craig without a water supply. Once the siege was over the Vikings plundered the fortress, taking many of the defenders captive.

Aftermath

The

Annals of Ulster The ''Annals of Ulster'' () are annals of History of Ireland, medieval Ireland. The entries span the years from 431 AD to 1540 AD. The entries up to 1489 AD were compiled in the late 15th century by the scribe Ruaidhrí Ó Luin� ...

record that once the siege had ended, a fleet of 200 ships transported the prisoners to Dublin. Alongside these prisoners were others, including Picts, Scots and

Northumbrians Northumbria () was an early medieval Heptarchy, kingdom in what is now Northern England and Scottish Lowlands, South Scotland. The name derives from the Old English meaning "the people or province north of the Humber", as opposed to the Sout ...

, who had been captured by Ímar and Amlaíb in previous raids. The fate of these prisoners is not known, but with Dublin at the time being one of Europe's premier slave markets it is likely they would end up as slaves. Following the siege of Alt Clut's royal and religious centre, the kingdom moved upriver to

, while Dumbarton Rock may have become a Viking outpost for a period. After this shift the kingdom became known as the

. It is possible that Arthgal escaped the siege and sought safety in Pictland, or alternatively he may have been among the prisoners taken back to Dublin by the Vikings. In 872, Arthgal is recorded as being murdered, possibly on the advice of Constantine I of Scotland. The kingdom was severely weakened by the siege, as its main fortress had been razed and its political structure was in disarray. The finding of some Norse style ruins in the Clyde area seems to suggest that the fall of Dumbarton led to more Norse influence in the area and the opening up of the kingdom to Norse settlement. It is likely Strathclyde during this time began to fall into the sway of

Alba ''Alba'' ( , ) is the Scottish Gaelic name for Scotland. It is also, in English-language historiography, used to refer to the polity of Picts and Scots united in the ninth century as the Kingdom of Alba, until it developed into the Kingd ...

. Nonetheless, Strathclyde is documented in battles and royal records to have existed as an independent kingdom up until some point in the

11th century The 11th century is the period from 1001 (represented by the Roman numerals MI) through 1100 (MC) in accordance with the Julian calendar, and the 1st century of the 2nd millennium. In the history of Europe, this period is considered the early ...

, when it was peacefully incorporated. The local Cumbric culture would go extinct soon after, dying out at the latest around

1300 The year 1300 ( MCCC) was a leap year starting on Friday in the Julian calendar. It was the last year of the 13th century, and the first year of the 14th century. The year 1300 was not a leap year in the Proleptic Gregorian calendar. January ...

. Arthgal would be succeeded by his son Rhun ab Arthgal, who became the King of Strathclyde after his father's death. It is likely that Rhun ruled as a subordinate of Constantine, who was his brother-in-law, providing a possible motive for the death of Arthgal.

References

Sources

* * * * * * * * * * {{DEFAULTSORT:Dumbarton 870 870s conflicts Sieges involving Scotland 870 9th century in Scotland Sieges involving Norway Battles involving the Vikings 9th century in Norway Attacks on castles in Scotland Sieges of the Middle Ages Slave raids Military history of Dublin (city) Looting in Scotland

Siege A siege () . is a military blockade of a city, or fortress, with the intent of conquering by attrition, or by well-prepared assault. Siege warfare (also called siegecrafts or poliorcetics) is a form of constant, low-intensity conflict charact ...

History of West Dunbartonshire