A friend of mine and I discussed this, and he suggested getting under with an Abschneiden, but I pointed out that that would only work if the Schnappen was done with the hands much too high (which, admittedly, is how most people do it, I’m sad to say). Correctly done, however, a Schnappen is more of a thrust of the pommel over your opponent’s hands with almost no lifting of your hands at all. And since the main Abschneiden from below requires the enemy’s hands to be raised up, that wasn’t it. Nor could the Abschneiden against a Zwerchhau work since you can’t really get your blade around correctly.
But then I looked more closely at the other Abschneiden—the one I never see anyone demonstrate or include in books any more (Tobler has it in “Secrets of German Medieval Swordsmanship,” but he does it incorrectly). The text says:
“Item, wann du im mitt ainem haw oder sunst starck vff sin Schwert bindest, laust er dann sein schwert abschnappen von dem dinen vnnd schlecht dir oben zuo dem kopff, so verwende din schwert mitt dem gehültz für dein haupt vnd schnyd im vnden durch sin arm; vnd setz mitt dem schnitt den ort vnden an sin brust.”
“If you bind strongly against his sword and he then snaps his sword over yours to strike at your head, wind your sword with the hilt in front of your head and slice under his arm. As you slice, set the point down into his chest.” Ringeck ff. 45r-v.
To be honest, I hadn’t looked at this much because I was simply going by the interpretation in Tobler, and it didn’t seem to offer much that the other Abschneiden plays didn’t—except for that word “abschnappen” or “snaps.” Despite the fact that it actually talks about an abschnappen, I had been looking at that word more generically—i.e., that he simply raises his hands and does a cut. Then I realized how foolish I’d been: Of course this was the counter to the Schnappen, and it had been staring me right in the face, if only I hadn’t been so canalized by accepting the incorrect interpretation in “Secrets.”
Tonight we tried this technique out for the first time, and it works amazingly well. It will not succeed against a Schnappen that is done fast and correctly, but that’s true of many counters—they only work if your opponent hesitates slightly or does something a bit off. But the action is fast and extremely effective when done correctly. The biggest trick is to wind quickly and lightly under your opponent’s arms; don’t treat it like a wide, powerful Unterhau; this is a Schnitt, not a Hau. Try to make first contact ahead of the middle of your blade on the underside of his arm, and then slice by pushing along under his arm as you drive your point into his chest. Also, don’t pull back any farther than you need to—don’t make contact near your point because that will make the technique take too long.
You can see a video of the technique here: http://www.youtube.com/watch?v=hh1UwpTLVoc
Edited to add: I should point out that my friend and colleague, Dave Clarke, figured this out before I did, and I would have known that had I not misunderstood his e-mail to me on the subject.