[1/2]

For, wanting to say to anyone that Amadís never existed in the world, nor any of those other adventurous knights of which many books are filled, would be like trying to persuade someone that the sun does not shine, or that ice does not freeze, or that the earth does not bring forth sustenance... let [the deniers] dare to say to me that the valiant Portuguese Juan de Merlo was never a knight errant, nor that he went to Burgundy and fought there in the city of Ras with the famous Lord of Charni, called mosén Pierres... [let them deny likewise] many other heroic deeds done by Christian knights, either within the boundaries of this kingdom or without, the which are so authentic and true, that I say again that whoever would do so, is completely bereft of good reason.

This quote from Miguel de Cervantes's Don Quijote, which I have translated from the original above, is an interesting point of departure for answering your question. Don Quijote's defense of the historicity of the romances of chivalry mentions in the same breath knights from fiction - such as Amadis of Gaul, Lancelot of the Lake and the Twelve Peers - and those that actually went on adventures in real life - besides Juan de Merlo, he talks about Fernando de Guevara and Suero de Quiñones among others. Now, you may be asking what relevance don Quijote's ravings have with your question. He in reality is making a conclusion which is the opposite of your question: since there were knights who went on adventures in real life, such as Suero de Quiñones, then we ought to take as true all of those romances which depict knights going on quests. After all, it wouldn't be too out of the ordinary!

The reality of the knight-errant - at least in Spain at the end of the Middle Ages - was one which not only drank from the well of fiction, but contributed to it as well. As demonstrated by the genre of the crónica particular (a kind of historic document that details the life and deeds of a specific person), there was such a thing as a knight-errant; rather than hunting down monsters or going on mystical quests, however, the knight-errant rather concerned himself with winning fame or riches where he could. Although a great many examples could be brought up here, for the sake of brevity and not being prolix, I will mention two specific cases of knight-errantry in the Middle Ages - the lives of Suero de Quiñones and Pero Niño - as well as the rather chivalric reality of the Conquest of the Americas. A good book on the subject with numerous examples is Martín de Riquer's Caballeros andantes españoles; I don't know however if it has been translated into any other language.

Suero de Quiñones (1409-1456), then, was particularly famous at the end of the Spanish Middle Ages for carrying out a deed proper of the romances of chivalry: in order to win the hand of his lady-love and show that she was the best among her peers, he proposed to break 300 lances against any adventuring knights that would meet him on the Bridge of Óbrigo in León. The proclamation of this joust, however, makes it clear that Suero de Quiñones had been influenced by the chivalric literature which was in vogue at the time. We ought not to forget that latter half of the Middle Ages saw the rise of the French Vulgate cycle, as well as other works important to the genre such as Malory's Le Morte D'Arthur or the aforementioned Amadís de Gaula. Before considering the joust itself, let us turn to some of the articles of proclamation, which I below will translate from the chronicle titled El libro del Passo honroso; I believe that they're "novelesque":

I, Suero de Quiñones, knight and natural vassal of the most noble and mighty king of Castile, our lord... notify and make known the conditions of my enterprise...:

[Article IV]: The fourth article is that any lady of honor who should pass by the place in which I and the already named knights and gentleman will be, or within a half-league thereof, who isn't accompanied by a knight to undertake the already stipulated joust for her, must forfeit the glove of her right hand.

[Article VI]: The sixth article is that, since there are some men who do not love truly, and they may want to save the glove of more than one lady, let them not be allowed to do so...

[Article XXII]: The final article of my deliberation is that it be made known to all the women of the world, and likewise to all the knights and gentleman that should hear the aforesaid articles, that if the ladies whose possession I am should pass by the aforesaid place where I shall be, then she may go freely without losing the glove of her right hand, nor shall any other knight save me do arms on her behalf, for there is no one in the world who can do them as truly as I.

Such declarations may seem familiar to the reader of chivalric romances. Consider the following excerpt from Anthony Munday's translation of Palmerín de Oliva, in which the prince of France declares a joust to prove that his lady is the most beautiful of them all:

Lordes and Ladies, who with such advantage have chatted on beautie, understand that such as you have yet spoken of, or severally in your owne thoughts shall thinke uppon: may not be equall with one that I knowe, even she that is Ladie and commaunder of my hart, whose beautie is so far beyond all other... I will make good my words by deedes of Armes, against anie Knight whosoever that dare saie the contrarie... I will be in open fielde in my Tent, where I will erecte a statelie monument on the toppe whereof shall bee her figure whose Knight I am, and there will I defende it in this honorable quarell against such Knights as will Combat for the beautie of their Ladies, I affirming mine to excell all others in perfections (pp. 205)

Rather than losing gloves, however, the stake of these battles are effigies of the respective knights' ladies: "if Fortune frowne on them in such sort as they be vanquished, they shall there (i.e., in the tent) leave their Ladies image, to be placed under my Mistresse as her subject." Just as many knights, both foreign and domestic, will test their mettle against this fictional prince of France, likewise Suero de Quiñones will joust with knights from all over Europe on the Honorous Pass. In his crónica particular, the aforementioned Libro del passo honroso, the name of every opposing knight is listed along with their place of origin. The knight who came from the furthest distance away, if I don't misremember, was one called Arnaldo de la Floresta Bermeja; or, as he's known in his native German, Arnold von Rottenwald. Thus, we may say, Suero de Quiñones provided the quest - an enterprise to prove who had the most perfect lady - and the adventurers came to him.

As opposed to Quiñones's rather static enterprise, the aforementioned Pero Niño (1378-1453), as recorded in his chronicle titled El victorial, was quite errant. From his native Spain, he was to travel to France, Britain and to the Mediterranean in the service of his lord. As Niño's standard-bearer relates in El victorial, the Spanish knight began his career during the siege of Ponteverda. One cannot help but perceive the "novelesque" quality of that first combat, which I translate from the original Spanish below:

Within the village there was a very famous foot-soldier whom they called Gómez de Domalo; he was a passing (rezio) fighter. He harried Pero Niño, pressing him hard. And Pero Niño desired to draw close to him to wound him, but Gómez defended himself with his shield in such a way that [Niño] could not land a hit on him. Once however Pero Niño closed with him, and [Gómez] likewise with [Niño], such that they delivered powerful blows on each other's heads; Pero Niño said that from that blow, sparks flew out from his eyes.