Siege of Dumbarton

The Siege of Dumbarton took place in 870, where the British fortress at Dumbarton Rock was besieged by a Viking force from Ireland. The Britons were defeated after four months when they ran out of water, and the attackers returned to Ireland a year later with a great deal of slaves and plunder. The event forced the Britons to move their capital to the vicinity of Partick and Govan, which resulted in the transformation of the Kingdom of Alt Clut into the Kingdom of Strathclyde.