HOW TO SURVIVE THE DARK AGES

The collapse of Roman rule in Britain left a vacuum that numerous powers competed to fill - but only a few realms endured. How did some thrive while others vanished or were vanquished? Thomas Williams offers six crucial survival tips for would-be rulers of early medieval kingdoms

- Thomas Williams

1 Go big or go home

After Roman rule collapsed at the start of the fifth century, everything changed in Britain - politically, socially, culturally and economically. Migration from northern Europe and around the Irish Sea contributed to the development of new kingdoms across the island that competed for power, or just for survival, until the advent of the Vikings marked a watershed at the end of the eighth century. Some of these kingdoms - Wessex in south-west England; Mercia in the Midlands; Northumbria in the north-east; East Anglia; and Gwynedd in north-west Wales - left an enduring legacy.

Others sank with barely a trace. So what factors brought long-term success? Growth was one key strategy. It wasn't a universal prerequisite - East Anglia, for example, remained largely static in size and shape until the Viking Great Army conquered it in AD 869. But most of the big beasts of early medieval Britain were realms that pursued aggressive, expansionist policies.

Take Northumbria, itself formed from the merger of two smaller kingdoms, Bernicia and Deira. It swallowed up several near neighbours, and had a crack at others.

Mercia was the midland realm with perhaps the greatest ambitions of all particularly during the reign of Offa (ruled 757-796) and his successor Coenwulf (r796-821). In the eighth century, it controlled an empire that extended from the Welsh borders to the Wash and south to the Channel. At its height, Mercia could claim overlordship of Sussex and Ken Hwicce, Lindsey and parts of Wales.

Wessex, the south-western realm that was later the only survivor of the Viking cataclysm, entered the mid-ninth century in control of all of Britain south of the Thames.