Arthurian legend

The political situation:
In the fifth century, the Romans settled in Great Britain and dominated the island, even if the Scots (people Celtic came from Ireland which will end up, in the sixth century, by settling on the west coast ofScotland) and the Picts (pre-Celtic people of Scotland), among others, remain rebellious.

But, from 486, with the conquests of Clovis and the invasions of the Vandals, Visigoths and Ostrogoths, the Roman Empire weakens strongly in its western part. The Romans then lose interest in Great Britain to focus on the defense of the Empire, which will not prevent its fall in the 490s.

The Saxons (ancient people Germanic which had expanded south and raided Gaul, newly arrived in Britain) took advantage of this to try to take over the whole island. 

Internal conflicts:
The various leaders Bretons and Welsh are then divided by incessant quarrels, and spend their time fighting among themselves, without much success.

All these kings, postulants to a unifying throne, suffer from a problem of legitimacy: the various invasions have brought about a great diversity of peoples and cultures in the kingdom. No leader succeeds in being recognized throughout the kingdom, and by all peoples. There is, therefore, no supreme leader, much less a king who commands all the inhabitants of Great Britain.

But in front of the important threat of invasion of the Saxons they all line up under the banner of a named Artorius.
This warrior, probably born around 470-475 in Cornwall, is the leader of a highly mobile band of mercenary horsemen. Everyone sees him as the only person capable of standing up to the invader. 

Artorius in power:
Artorius was therefore appointed commander-in-chief of the new army and, all united, the Breton and Welsh kings won, somewhere in the southwest of England around 500-518, a great victory which stopped the invader for about forty years. This is the Battle of Mount Badon (or Bath, or Badbury).

When Artorius died in a great battle, near Camelford in Cornwall, around 540-542, it was the end of Breton independence: at the end of the century, the Saxons occupied three quarters of the island .

The body of Artorius is secretly buried in Glastonbury by his lieutenants, who are anxious to hide his death so as not to demoralize the troops. 

The results :
Faced with the invasion, thousands of Bretons crossed the sea to settle in the Armorican peninsula, to which they give the name of Brittany. They find there compatriots who have arrived since the fourth century. They remain in very close contact with the Bretons who remained on the island. Both keep alive the memory of Artorius and make him a king, which he never was in reality.

On the other hand, the problem of legitimacy always arises, and even more so, after the seizure of power by William the Conqueror (1027-1087), Duke of Normandy, in 1066. The king is a Norman, a minority people. And this situation is all the more boring as the rival dynasty does not have this problem: the Capetians present themselves as the descendants of Charlemagne.

To overcome this great disadvantage, the Normans encouraged the clerics to disseminate what is already the legend of Arthur (Roman name for Artorius), and more particularly the myth of his dormition and his imminent return, with the aim of s' ally the Welsh and defeat the Anglo-Saxons. 

The creation of the myth:
At first, therefore, the legend says that Arthur is not dead. Seriously wounded during the battle of Camlann, he was transported by his sister, the fairy Morgana, to the island of Avalon, where he is being treated, waiting to be able to return to take the head of his people: it is Breton hope.

But Henry II (1133-1189) will finally confiscate the legend of Arthur, by presenting himself as his legitimate heir, and put an end to Breton hope. For propaganda purposes, he asks for language romance of the Historia Regum Britanniae, commissioned in 1138 by his father, for the same purpose, from Geoffrey of Monmouth.
The king, inside his kingdom, needs the support of the Bretons against the Saxons who do not accept Norman domination. But the Bretons are not ready to rally to the Plantagenets banner because of Breton hope.

The novel, in three parts, ends with the description of Arthur's reign: his accession to the throne, his marriage, the creation of the Round Table, until the death of the sovereign.

Finally, in 1191, we discovered the tombs (and the skeletons) of Arthur and Guinevere in the cemetery of the abbey. As for the Isle of Avalon, she is identified with Glastonbury Abbey. This puts an end to Breton hope. 

The extension of the myth:
Around 1100, the legend is so present and strong that the bards graft myths folklore, geographical particularities, Christian traditions and small later local heroes (Yvain for example), …

In two or three centuries, therefore, Arthur has become the pivot around which revolves a whole system of independent stories originally, and this set ends up forming a vast and rich reservoir, an immense and inexhaustible myth.

It was Robert Wace, in his Roman de Brut, in 1155, who gave the myth a courteous color. Arthur becomes the ideal monarch, a model of humanity, valor, generosity and delicacy. He was also the first to mention the Round Table, a political symbol of courteous society.

The Arthurian legend is, from the end of the eleventh century, disseminated throughout Europe, and even beyond, by the professional storytellers who accompany the armies leaving for the Holy Land on the occasion of the first two crusades.