At the Battle of Frankenhausen, part of the German Peasants' Revolt, between 3 and 10,000 entrenched peasants died for the loss of a reportedly six Landsknechten. Although it took place later than the period you mentioned the vast majority of Landsknechten at the time were armed with pikes or long swords. It illustrates the effect that well armed, professional soldiers can have against poorly armed levies.
Over the course of the revolt it is estimated that around 300,000 peasants took part of which 100,000 died. As none of their demands were acceded to it's obvious their huge numbers alone were not considered a serious threat to the status quo.
Source is Douglas Miller's Armies of the German Peasants' War.
In battle, a very small number of profesionally trained soldiers can take out a very large amount of poorly trained or unexperienced opponents. Without discipline, the line of the lesser trained will fail very fast, and most of the kills will be inflicted during the "poursuite", to use napoleonics terms.
/u/Pleascah already gave an exemple here. Another famous example is the battle of civetot, and the ultimate defeat of the people's crusade.
Now, for alone vs the world fight, it would mostly depend of the opponent facing each other. As you would expect, swordsmanship is not innate, and was an important part of the education of knights. An experienced fencer vs a an unexperienced one is the same as a professional NBA player vs you playing basketball. here is a pdf covering the basic of 2H fighting. it's very well sourced (last page), but sadly is in french only. I have yet to find something remotely equivalent in english.
Also, and contrary to popuar beliefs, war plate armor was rather light and knights could fight on foot. The misconception is coming from the joust armor, which was only used for jousting, and was so heavy that knights often needed help to climb on the horse. They are easily spottable with their "grand guard" metal plate bolted on the left shoulder. These kind of armor are not made for war at all, as they are very impracticable, limiting the movement and vision a lot.
This is a jousting armor and it's made for this, where the tip of the spear of a launched knight has nearly the same impact power of a small caliber canonball.
these are ''battle" armor, often lighter to what a modern infantry man has to carry. They are much more move permitive than modern ballistic armors, and you can even find some guys on youtube doing stuffs like saltos in it. These kind of armor practically makes you invulnerable to everything you will encounter on the battlefield except grapling and blunt weapons. Even sword fighting was just a way to tire your opponent before using your lefthander to kill him. (or more likely take him hostage for mad profits)
Add the invulnerability of the armor to the range and efficiency of 2h sword vs an unarmoured target, knights were pretty much invulnerable for an unexperienced foe. If you take in account the physical condition of a well fed knight vs the malnutrition of a serf, the fact that the knight don't care killing it's opponent while the rabble is trying to capture the knight alive for CRAZY amounts of money, yes, the fight is completely one sided. The only limit is the knight physical condition. And no, this is not because a 2h swords is heavy. They are not. It's because fighting is tiring. Also, synchronized assaillant can tackle him down (your center of mass is still higher with an armor), and once pinned attack him trough the joints.
What movies shows is the heroes dispatching hordes of ennemies, jumping around, without breaking a sweat. In reality, you would expect the knight to be very economous of it's moves (not jumping around) and resting as much as possible between each pass, adopting a rather grotesque guard position rather than the nochalent herobright smiling pose seen in hollywood. A very important component of western fencing is also positionning (stairs spins upward clockwise for a reason. a right handed attacker climbing can't efficiently use his main arm) and stepwork. The modern martial sport that would look like the most like medieval fencing for it's pace and positionning is boxing. Not the kungfu karate explosion of energy dynamic stuff that look so much better on screen. Despite using swords, the variation of modern fencing and kendo are only one dimensional, and are not "realistic" positionning.
Please do note that before the XVth century, war was extremely limited in scale, with army rarely seen over the scale of the ten thousand, and were mostly sieges. It was nowhere near the swift bloody open field battles that showed up later in the renaissance.
For a follow up question, a knight on foot with a plate armor, longsword and rondelle would totally destroy a samourai on foot wearing his ō-yoroi, katana and tanto. (assuming more or less equal skill and physical condition). Japanese weapons and armor are heavier and much more brittle than their european counterparts. (A traditional katana is heavier than an equivalent sword). katana are made for cutting because they would just break if used for anything else.
The blame is to be put on the lower grade iron japanese had to works with, full of impurities. The complex craftmanship necessary to create a blade was due to these impurities. When japanese had access to early iron age weapons quality, the european had access to naturel reserve of iron mixed with intersting addidive (such as phosphore), as well as crucible steel imported from india (Ulfberth swords). A frank sword from 800 is superior in every aspect to a katana from 1600. now add the technological progress over 800 years...
Keep in mind that plate-clad knights that were pretty much invulnerable to almost any kind of common sword slash or pierce movement (even early gunpowder era bullets and crossbow bolts, to some extent), limiting the vulnerable spots to the joints (such as in the armpits and groin). Long poled weapons like halberds, pikes or longswords could exploit such weak spots more easily, but we're (I think you are, at least) considering the knight to be fighting a band of peasants, for example.
Plate armour was virtually sword-proof. It also protects the wearer well against spear or pike thrusts and provides decent defence against blunt trauma.
Meaning that it would be pretty difficulty for a peasant (or poorly armed/trained soldier) to score a hit in such places considering the situation (in middle of a battlefield), the poor training versus the knight's extensive training on weapon handling/armor conditioning and, most importantly, most knights fought at the back of a horse, making it even more difficult to land a hit in one of those aforementioned areas while the horse was charging, or the height difference for that matter. Plus, the horse was also armor-clad.
Just to clarify, do you mean one at a time, Nigel Powers style, or all at once? Very different situations.
For the sake of specificity, are you talking about a trained knight in full plate presumably armed with a sword and a heater shield if we are picturing the classic image of a knight?
The impression I get of your scenario is the knight fighting on foot against a dozen peasants with no real armor or training and armed with perhaps axes, flails or spears?
Or did you mean a knight fighting against a dozen men at arms with combat experience and some less expensive armor (some chainmail, a metal helmet), and well made spears or maces?
Your question is very broad.
For example, I imagine by knight you mean someone who was very well armed and armored. How well equipped they were depends on a huge variety of factors (like if they had any money to pay for good equipment) as well as the specific place and time period.
And then what does 'poorly trained' mean in the context of you using the word 'soldiers'? Do you mean relatively poorly trained professionals? Completely untrained levies? Somewhere in between?
What do you mean by them being poorly equipped? Relative to the average? Relative to our theoretical 'knight'?
But even if we ignore this, tons of psychological and contextual factors come into play. What if the 'knight' brutally mutilates one of the soldiers and the others are too afraid to keep fighting? Does this count as 'coming out on top?'
To clarify, this is not meant to be read as an attack but to highlight the inherent difficulties of answering these kinds of questions. You have no idea how often I get messages asking me 'who would win, a samurai or a viking'.
Anyways, I assume that you mean a situation where the 'knight' is heavily armed and armored in such a way that it is not impossible to harm him but very difficult for his dozen or so 'poor' opponents, who have a modicum of training but not quite a lot as well as lacking adequate arms to quickly defeat the knight as well as enough armor to be confident enough to stand against the knight on equal terms.
For example, a movie scene where a hero strolls in, casually carves up a dozen or two soldiers and walks away without a sweat.
Well the answer is probably going to be NO.
What many people take for granted is that actual hand to hand combat is incredibly tiring. For most anyone. Being too tired to continue fighting is always a distinct possibility where every swing, thrust and movement is tense and costs lots of energy.
And being ganged up on even two or three to one with no way to run generally means death for even skilled warriors. Yes, yes there are exceptions to this everywhere and that's why those exceptions are legendary or almost mythical.
A dozen men who can cooperate even a little to corner and then attack simultaneously? Unless the knight has some very serious advantages coming into this fight, he's not going to win. Coming out of an even fight against anything more than 4:1 odds could be considered a small miracle.
Even on endurance alone, our knight is outmatched with such stacked numbers.
And yes, I know there are 'styles' or 'martial arts' that are all based around fighting multiple enemies. Sure, you can imagine dozens of ways our hero might get out of a jam surrounded by dozens of bad guys. This is basically the climax of every action movie we've ever loved.
Well, there's a good reason soldiers who fight with spear, axe, and sword have fought in groups for millennium.
And as others have said here and elsewhere, for much of military history, the vast majority of casualties have been inflicted during routs, where the killing was much more about hunting down those who had broken ranks and were now individuals and no longer in the safety of a fighting group. Very much like our brave knight!
So only in the most fortunate of circumstances would the knight come out on top. Of course, there are so many different factors that one could imagine to influence this fight it's essentially impossible to give a definite answer besides general ones. Environment, morale, external knowledge, alternatives, previous events, discipline, cause for the fight, etc etc etc.
I'm going to suggest that you ask this question over at /r/wma as well. I don't say that you will get a better answer, but it will certainly be different inasmuch as the nice people over there are accustomed to training and hacking and stabbing at each other with large historical European weapons and accordingly, may be able to provide some interesting insights. This is especially true since some of them have dedicated years to researching the relatively few primary sources that exist for their particular area of interest.
Edit: also, the answer to your question is going to be hugely affected by whether or not your knight is mounted. A mounted knight will be a much tougher nut to crack. In fact, I think that you'll have to be far more specific about everything if you want a real answer. I mean, a dozen or so veteran pikemen would probably settle your knight's hash in no time at all whether he's on horseback or not, whereas if they have no training whatsoever, then yeah, they are basically sitting ducks.
Most of the answers on these thread are assuming that the knight is fighting on the ground. But What if he is riding a horse? I know that cavalry charges are meant to be performed in a group, but will a single cavalier changing be merely less effective or more dangerous for the caviar as well?
