An uneasy peace lay across the British Isles following Alfred the Great's victory over the Viking invaders. The kings of England, Scotland, Ireland and Wales, and the freshly settled Danes, sensed a time of opportunity. Ambition smouldered within the courts, and securing loyalty from within was paramount to both the success – and survival – of a ruler.

Assuming the role of the English, the Gaels, the Welsh, the Great Viking Army or the Viking Sea-Kings, players of Thrones of Britannia must master the dark arts of politics, employing every method from the arrangement of marriages and the gifting of estates to bribery and – in extreme cases – assassination.