Until William s consolidation of the Norman conquest, the British island of Great Britain — as opposed to Little Britain or the Gallic province of Brittany — went through a timeline where a series of kingdoms cohabited a small km² relative to the continent of Europe, which at the same time witnessed clashes between empires. At the beginning of the post-Roman period, Britain was made up of more southeastern city-states, militarized monarchies in the north-central, and tribal principalities in the rest of the territory. Religion in Britain was an important unifying factor among the island peoples and nations; and was the common identity in the fight against the Pagan Germanic invasions. The simulation will cover more than a thousand years (410 to 1453 AD) of the history of the island of Great Britain, from the end of the Roman province — that is, the end of the Old Age in the area — from Britannia to the end of the Medieval Age. In the military field the organizational structures of the main continental invaders against the great Celtic island, the Anglo-Saxons (Germanics of Germany) and the Normans (Germanics of France) will serve as models.
