Here's some info =)
Amadis de Gaula (original Portuguese version) (English: Amadis of Gaul, Spanish: Amadís de Gaula) is a landmark work among the knight-errantry tales which were in vogue in 16th century Iberian Peninsula, and formed the earliest reading of many Renaissance and Baroque writers.
The first known printed edition was published in Zaragoza in 1508, by Garci Rodríguez de Montalvo (or Garci Ordóñez de Montalvo). It was published in four books in Castilian, but its origins are unclear: The narrative comes from Portugal, originates in the late post-Arthurian genre and had certainly been read as early as the 14th century by the chancellor Pero López de Ayala as well as his contemporary Pero Ferrús.
Montalvo himself confesses to have amended the first three volumes, and to be the author of the fourth. Additionally, in the Portuguese Chronicle of Gomes Eannes de Azurara (1454), the writing of Amadis is attributed to Vasco de Lobeira, who was dubbed knight after the battle of Aljubarrota (1385). However, it seems that in fact the work was a product of João de Lobeira, not the troubadour Vasco de Lobeira, and that rather than originating with him it was the revision of an earlier work from the beginning of the 14th century.
In his introduction to the text, Garci Rodríguez de Montalvo explains that he has edited the first three books of a text in circulation since the fourteenth century. Montalvo also admits to adding a fourth as yet unpublished book as well as adding a continuation (Las sergas de Esplandián), which he claims was found in a buried chest in Constantinople and transported to Spain by a Hungarian merchant (the famous motif of the found manuscript).
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The story narrates the star-crossed love of King Perión of Gaul and Elisena of England, resulting in the secret birth of Amadís. Abandoned at birth on a barge in England, the child is raised by the knight Gandales in Scotland and investigates his origins through fantastic adventures.
He is persecuted by the wizard Arcalaús, but protected by Urganda la Desconocida (Urganda the Unknown or Unrecognized), an ambiguous priestess with magical powers and a talent for prophecy. Knighted by his father King Perión, Amadís overcomes the challenges of the enchanted Insola Firme (a sort of peninsula), including passing through the Arch of Faithful Lovers.
Despite Amadis' celebrated fidelity, his childhood sweetheart, Oriana, heiress to the throne of Great Britain, becomes jealous of a rival princess and sends a letter to chastize Amadís. The knight (later famously parodied in Don Quixote), changes his name to Beltenebros and indulges in a long period of madness on the isolated Peña Pobre.
He recovers his senses only when Oriana sends her maid to retrieve him. He then helps Oriana's father, Lisuarte, repel invaders. A short time later he and Oriana scandalously consummate their love. Their son Esplandián is the result of this one illicit meeting.
Rodríguez de Montalvo asserts that in the "original" Amadís, Esplandián eventually kills his father for this offense against his mother's honor; however, Montalvo amends this defect and resolves their conflict peaceably.
Oriana and Amadís defer their marriage for many years due to enmity between Amadís and Oriana's father Lisuarte. Amadís absents himself from Britain for at least ten years, masquerading as "The Knight of the Green Sword". He travels as far as Constantinople and secures the favor of the child-princess Leonorina, who will become Esplandián's wife. His most famous adventure during this time of exile is the battle with the giant Endriago, a monster born of incest who exhales a poisonous reek and whose body is covered in scales.
As a knight, Amadís is courteous, gentle, sensitive and a devout Christian. Unlike most literary heroes of his time (French and German, for example) Amadís is a handsome man who would cry if refused by his lady, but is invincible in battle and usually emerges drenched in his own and his opponent's blood.
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Amadís of Gaul is frequently referenced in the satirical classic Don Quixote, written by Miguel de Cervantes in the early 17th century. The character Don Quixote idolizes Amadís, and often compares his hero's adventures to his own.
And to believe that someone like Cervantes, indeed, praised Amadis as a child (like those tough critics who watched LOTR and then became children, seeing it over and over =) )... because, having mentioned Amadis more than 45 times in Don Quixote! That's gotta count for something! =)