Historia Regum Britanniae, or History of the Kings of Britain, is a work by Geoffrey of Monmouth from around the 12th century. This work is notable for kickstarting British history, with some Artistic License taken to fill in the blanks Geoffrey couldn't get from Bede or other sources. For a long time, it was considered a Universe Bible for British History in the Middle Ages, with some hints of propaganda. It can be considered a founding myth for several ethnic groups in Britain.
After a brief introduction the history of the Britons starts around The Trojan War after which Brutus, a great-grandson of Aeneas, sets sail with a group of his people to found a new empire, which happens to be Britain.
The most lasting legacy of Geoffrey's Historia is the invention of King Arthur and Merlin in the form that became canon throughout the Middle Ages and that we can still recognize today. Two other figures from the book that are still known today by way of Shakespeare's dramas are King Lear (Leir) and Cymbeline (Kymbelinus).
In his outline of British history, Geoffrey largely follows the three hundred years older Historia Brittonum, though he provides a lot more material.
The book can be found here if you want to read it. Your local bookstore probably has a copy as well.
Historia Regum Britanniae provides examples of:
- Ancient Grome: In spades. Brutus of Troy, anyone?
- Artistic License History: Very much so. Even 40 years after Geoffrey's death, William of Newburgh extensively criticised Geoffrey for his history, and even went so far as to say his work "is a fiction, invented either by himself or by others".
- Canon Welding: Older Than Print example. The story weaves The Aeneid, The Iliad and The Odyssey into the Arthurian mythos by having Brutus sail to pre-Roman Britain and founded an empire there with New Troy (aka London) as the capital setting the stage for Arthur and the Knights of the Round Table to exist.
- Composite Character: Geoffrey's Merlin is loosely based on the legendary bard Myrddin, but he also casts him in some episodes that earlier writers attributed to Ambrosius. He therefore claims that Merlin "was also called Ambrosius". Nevertheless, the original Ambrosius still figures as a separate character (Arthur's uncle) in Geoffrey's narrative.
- Dedication: To Robert, First Earl of Gloucester.
- Death by Childbirth: Brutus' mother dies in giving birth to him.
- Dreaming of Things to Come: When Brutus sleeps in a temple of Diana, she reveals to him in a dream that he is destined to go to Britain and found a kingdom there.
- Early Installment Weirdness: There is no Sword in the Stone, no Round Table and no Lancelot (Guinevere hooks up with Mordred instead), Merlin doesn't actually serve or mentor Arthur, and no Morgan Le Fay, but Arthur has one sister named Anna. Morgan does appear in Geoffrey's related work Vita Merlini where she lives in Avalon and uses her magic for healing instead of evil.
- The Emperor: Arthur. As King of Britain he conquers the whole British isles, gains the allegiance of rulers of various tribes and lands including Iceland and Norway, and invades continental Europe and comes close to conquering the Roman Empire itself but is sidetracked by Mordred's rebellion.
- Evil-Detecting Dog: Merlin uses magic to disguise Uther as Gorlois and himself as a soldier so that Uther could trick Gorlois' wife into sleeping with him and thus conceive Arthur. Gorlois' dog can tell they're imposters, but Merlin uses a spell to calm it down
- Evil Nephew: A lot of rulers have these. Cordelia, Arthur, and Constantine III (along with an unnamed uncle of Constantine III's nephew Aurelius) fall victim to this.
- The Evil Prince: Used frequently. Constantine's nephew Aurelius Conan kills him, then imprisons an uncle who should have ruled after Constantine and kills their two sons.
- Founder of the Kingdom: Brutus.
- Hunting "Accident": Brutus accidentally kills his father Sylvius when shooting an arrow at a deer.
- Present-Day Past: Older Than Print. British society was apparently always like the feudal society of Geoffrey even during Brutus' founding of Britain. This isn't just Britain either Homeric Greece apparently had castles.
- The Promised Land: When Brutus finds Britain, as foretold by Diana, it is a paradisiacal land that abounds of natural resources.
- Public Domain Artifact: According to Geoffrey, Stonehenge was built by giants from "mystical stones" brought "from the farthest coast of Africa". The stones were magical so that water poured over them acquired healing power, and the giants used to cure all kinds of sicknesses by bathing in such water. It was situated on a mountain top in Ireland, until it was brought to Britain by Uther Pendragon and Merlin and re-erected in the exact same shape, so it would keep its mystical powers. This narrative seems to suggest the stones still have the power to heal, only nobody can remember which stone cures which sickness.
- The Usurper: Vortigern is an archetypal example.
- Waif Prophet: As a fatherless child, Merlin not only reveals the secret of why the walls of Vortigern's fortress of Dinas Emrys collapse every night, but also delivers a prophecy of Britain's future.