Stages in the Creation of the Arthurian Romance Tradition

Establishing Arthur as a Mythic Warrior/Leader with a Court of Named Notables:

Celtic antecedents: Nennius, Historia Brittanae [History of the Britains]--"Pendragon" is a dux bellorum (duke of battle, warlord) who leads the Welsh against the Romans in 12 battles, culminating in the Battle of Mount Badon); Wawayne or Gawayne narratives built upon Nennius and the Culchallain hero-legends of Irish and Welsh Celtic tradition.

***Geoffrey of Monmouth (1100-1155), Historia Regum Britanniae c. 1136 [History of the Kings of England]: purports to be a Latin translation of a "very old Anglo-Saxon book," no trace of which has survived; establishes a chronology of Arthur's birth, kingship, and death, including the involvement of his court mage and counselor, Merlin, and Arthur's conquest of Rome to establish a Continental English Empire--no Round Table, no Lancelot, no Tristan.

Robert Wace (1100-1175), Geste des Bretons [Deeds of the Britains], an Anglo-Norman (i.e., French) paraphrase of Geoffrey's Historia that adds the Round Table, the code of chivalry as a value system organizing Arthur's court, the tradition of knights undertaking quests or seeking adventures ("knights errant"), and emphasis on ceremonial court activity.

La3amon, Brut (c. 1205), a free translation of Wace in alliterative West Southern English that situates Arthur's kingship firmly within the English foundation myth which has the fleeing Trojan lord, "Brut," founding Londinium along the same lines that Virgil's Aeneid purported to record the foundation of Rome by the Trojan lord, Aeneas; adds description of the Round Table's origin as the queen's dowry, brought to Arthur from Ireland.

Introducing the French and Cornish Knights, Lancelot, Perceval, Galahad, Bors, and Tristan, and Bringing Arthur's Kingdom to Destruction

Chretien de Troyes (1140-1191), chaplain to the court of Marie de Champagne (later wife of Henry II, king of England and France, 1154-89), living in Provence (Modern France), a series of shorter verse romances of extraordinary artistry, all set in the Arthurian past and dealing with the struggles of profane and sacred love: Erec et Enide, Le Chevalier de la Charette [Knight of the Cart, a Lancelot and Guenivere romance], and Perceval le Gallois [Perceval of Wales, an unfinished romance which introduces the Holy Grail as the object of a sacred quest for Arthur's knights].

Vulgate Cycle: an immense linked set of romances found in many Old French manuscripts from C13-15, written by many authors (spuriously}claiming to derive from original MSS sources by Robert de Boron, and developing a coherent sequential narrative of the lives and conflicts of Arthur, Guenivere, Lancelot, Gawain, Merlin, Palomides (a Saracen knight), Tristan (imported from the German tradition), and the Grail Quest, now led by Galahad, Lancelot's illegitimate son--major "branches" include the Prose Merlin, the Prose Lancelot, the Prose Tristan, the Queste del Sainte Graal, and the Mort le roi Artu. 

Reintroducing Arthur's Story to the English

Harry Lovelich (c. 1320), a London member of the Skinner's Guild, translated the Queste del Saint Graal and the Prose Merlin into Middle English (only one MS of each survives)

The Alliterative Morte Arthure and the Stanzaic Morte Darthur, early C15 adaptations of the final branch of the Vulgate cycle in alliterating and rhyming stanzaic verse.  Both were known to Malory and the former was the source for nearly all of his "Roman War" segment.

Sir Thomas Malory, 1469/70 (pub. Caxton 1485), Kyng Arthur (?), a translation, increasingly free, of the French and Alliterative Middle English Arthurian tradition into a large body of Arthurian narrative