Athelstan

When the Romans, beset by invasion of their own, refused to come to the rescue, the Britons in their despair and misery turned for assistance to mercenaries from across the North Sea. Entire tribes began to migrate. One of these was named the Angles, another the Saxons, and a third the Jutes.

[...] behind this vision, of an agglomeration of kingdoms that might plausibly be termed ‘Englalonde’, there was to be found an infinitely more ancient ideal: that of an empire spanning the whole of Britain. Settled though it was by ‘peoples divided by language and separated by race according to their ancestors’ names’, yet the dream of establishing a pan-Britain order was one the many of them shared. In Wales, poets foretold a time when the whole island would once again be theirs; in the Highlands, the Scots pointedly termed their kingdom ‘Alba’, the venerable Gaelic word for ‘Britain’; in Canterbury, the archbishop regarded himself as Primate of the entire British Church. It was hardly to be expected, then, that Æthelstan, in the wake of his conquest of York, would rest content with laying claim merely to the rule of the English.

The story of how, over the course of three generations, the royal dynasty of Wessex went from near-oblivion to fashioning a kingdom that still endures today is the most remarkable and momentous in British history.