An army of Viking pirates that had besieged the English city of Canterbury for weeks took Archbishop Ælfheah prisoner and seized power. Siege of Canterbury: The siege of Canterbury was a major Viking raid on the city of Canterbury that occurred between 8 and 29 September 1011, fought between a Viking army led by Thorkell the Tall and the Anglo-Saxon defenders. The details of the siege are largely unknown, and most of the known events were recorded in the Anglo-Saxon Chronicle. September 29, 1011. Wiki link