Hey Triton,
There's an awful lot to comment about in this excellent article, one or two minor things I don't quite agree with the author on, but one thing at a time...
First, the question of One versus A dozen.
Yes, the scenario rings very true to me and I have no doubt at all that it happened exactly as described, but I doubt it would have worked against any but the most raw beginning student.
Without taking anything away from John Clements or his unquestionable skill, I have to say I consider this more of a "stunt" and "teaching tool" than anything really useful. As a teaching tool, I'd have to say that the author apparently didn't get the most important lesson to be learned from it. *
You see, the only reason Clements wasn't "killed" outright is because he wasn't fighting a group of 12, he was fighting 12 individuals acting without any sort of cohesion or coordinated effort.
I have on many occasions fought multiple opponents. Ive never fought twelve by any means but two or three is not terribly unusual.
When you fight two opponents, you must kill one of them very quickly as it won't take them long to figure out that you cannot have your sword in two places at one time. If one gets behind you, the game is over. You must constantly move and look for your "edge." That edge can be sunlight glaring in your opponent's eyes rather than your own, it can be a seemingly insignificant rise in the ground, or even shrubbery and foliage that will block your opponent's swing and "channel" him to where you want him to be rather than where he wants to be.
Had any two or three of the students in that class banded together to attack in concert, the outcome would probably have been much different. One student ties up Clement's sword, one keeps his dagger busy, and the third makes the "kill."
The only way to survive this tactic is to run away. (Highly advisable.)
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On the author's comments about where the swordsman carried his dagger, I firmly believe that most swordsmen of the time carried more than one dagger. The usual setup would have been a very stout dagger as the Main Gauche carried in a right side cross draw position, and a somewhat lesser dagger carried either behind the hip or in the small of the back. Primarily for close dagger work such as the author describes, but large enough to be pressed into service as a Main Gauche should the primary Gauche be lost in the heat of battle.
We don't see many paintings giving provenance to this because portraits were not done of the lowly swordsman, but rather portraiture was reserved for the wealthy class who's "gentility" and "nobility" would never publicly admit they ever engaged in anything so lowly and vulgar as a "knife fight." (Never mind that most portraits were Frontal views and give no clue as to what is behind the subject's back!)
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As to what Sport Fencing does and does not teach you, I hesitate to mention Sport Fencing for the same reason I hesitate to mention Tennis. Neither have anything to do with real sword fighting.
Sport Fencing is a fine sport, but it is fought "on line" at measured distance. There is no chance to maneuver for position or advantage, maneuvering is for the purpose of distance only. There is no "high ground" nor can natural obstructions be utilized, there is no opportunity for subterfuge or mis-direction. Indeed such behavior will cause you to be disqualified immediately. Sport fencing may teach decent blade work, but even this is of questionable quality since many techniques possible with the foil are not possible with a slower and heavier "real" blade.
I can almost guarantee you that a Sport Fencer has a better knowledge of the "nomenclature" of the technique than I do, but I haven't yet met a fencer that stood a chance against a real Swordsman.
There's much more to winning than pretty blade work.
*The lesson, for any who might not have figured it out by now, is that for "Battlefield Tactics" the rule is TEAMWORK!
) In that context a "tactical sword" is going to get you killed by some punk armed with a Saturday night special.