Dumbarton Castle

Dumbarton Castle (Scottish Gaelic: Dùn Breatainn, pronounced [t̪unˈpɾʲɛʰt̪ɪɲ]; Welsh: Alt Clut) has the longest recorded history of any stronghold in Scotland. It sits on a volcanic plug of basalt known as Dumbarton Rock which is 240 feet (73 m) high and overlooks the Scottish town of Dumbarton.

Dumbarton Rock was formed between 330 and 340 million years ago, during the Early Carboniferous period, a time of widespread volcanic activity in the area where Glasgow is now situated; over time, the softer exterior of the volcano weathered away, leaving behind a volcanic plug of basalt.

At least as far back as the Iron Age, this has been the site of a strategically important settlement, as evidenced by archaeological finds.

The people that came to reside there in the era of Roman Britain were known to have traded with the Romans. However the first written record about a settlement there was in a letter that Saint Patrick wrote to King Ceretic of Alt Clut in the late 5th century.

David Nash Ford has proposed that Dumbarton was the Cair Brithon ('Fort of the Britons') listed by Nennius among the 28 cities of Sub-Roman Britain. From the 5th century until the 9th, the castle was the centre of the independent Brythonic Kingdom of Strathclyde. Alt Clut or Alcluith (Scottish Gaelic: Alt Chluaidh, pronounced [aɫ̪d̪̊ˈxɫ̪uəj], lit. 'Rock of the Clyde'), the Brythonic name for Dumbarton Rock, became a metonym for the kingdom. The king of Dumbarton in about AD 570 was Riderch Hael, who features in Welsh and Latin works.

Merlin was said to have stayed at Alt Clut. The medieval Scalacronica of Sir Thomas Grey recorded the legend that says that "Arthur left Hoël of Brittany his nephew sick at Alcluit in Scotland." Hoël made a full recovery, but was besieged in the castle by the Scots and Picts. The story first appeared in Geoffrey of Monmouth's Historia Regum Britanniae. Amongst lists of three things, in the triads of the Red Book of Hergest, the third "Unrestrained Ravaging" was Aeddan Fradog (the Wily, perhaps Áedán mac Gabráin), coming to the court of Rhydderch the Generous at Alclud, who left neither food nor drink nor beast alive. This battle also appears in stories of Myrddin Wyllt, the Merlin of Geoffrey of Monmouth's Vita Merlini, perhaps conflated with the battle of Arfderydd, located as Arthuret by some authors.

In 756, the first (and second) losses of Dumbarton Rock were recorded. A joint force of Picts and Northumbrians captured the fortress after a siege, only to lose it again a few days later. By 870, it was home to a tightly packed British settlement, which served as a fortress and as the capital of Alt Clut. In 871, the Irish-based Viking kings Amlaíb Conung and Ímar laid siege to Dumbarton Rock. The fortress fell in four months, after its water supply failed. The kings are recorded to have returned to Ireland with 200 ships and a host of British, English, and Pictish captives. These prisoners may have included the ruling family of Alt Clut including the king Arthgal ap Dyfnwal, who was slain the following year under uncertain circumstances. Following the Viking destruction of the fortress, Dumbarton Rock does not appear on record again until the 13th century, and the capital of the restructured Kingdom of Strathclyde appears to have relocated up the Clyde to the vicinity of Partick and Govan.

In medieval Scotland, Dumbarton (Dùn Breatainn, which means "the fortress of the Britons") was an important royal castle. It is believed to be the place Sir John Menteith took William Wallace on the way to London after Wallace's capture.