For those with an Italian background, it is important to understand that a Nachreisen (following or chasing) is nothing more than an attack in Contra Tempo (counter-time).
Consider these quotes,
Contra tempo is when at the very same time that the adversary wants to strike me, I encounter him in shorter tempo and measure; and one needs to know that all the movements and all the reposes of the adversary are tempos, although at measure
Mezzo tempo is when at wide measure I strike the adversary in his advanced and uncovered arm, either that of the dagger or of the sword, with a thrust or cut, or alternately when I strike the adversary at narrow measure, as he moves himself to strike me or perform some other action; redoubling of blows is usually done in mezzo tempo.
This is a particularly good handwork, and he who is very skillful in it and knows well how to use it may properly be praised as a master. And chasing is executed thus: if your opponent cuts with his weapon either too far up or down, or too far out to the side, then you rush after him at his opening and thus prevent his cut coming to completion; for this may properly be used against those who fight with their cuts sweeping wide around them.
You can’t prevent a cut from coming to completion unless you are using a shorter action, which is what Capo Ferro refers to as a blow in mezzo tempo (middle time). And your arm won’t be exposed unless your weapon is “too far up or down, or too far out to the side”, a requirement for the use of a Nachreisen.
So while the German masters aren’t always clear on when to use a Nachreisen, but we can use this analogy and the writings of the later Italians to fill in the blanks.
Specifically, a Nachreisen requires the following conditions:
- You are fencing in measure, which is to say one fencer can wound the other with (wide) or without (narrow) taking a single step.
- Your opponent has exposed himself by either
- moving his sword too far away from his body in any direction.
- taking any action without a tempo
- using a large action while in narrow measure
- You can respond with a shorter action
So lets consider a play from Meyer,
When an opponent is fighting with you, then observe in which part he holds his sword. Now if he holds it in the right Ox, that is in the upper right quarter, then the moment he takes his sword away from there to change to the other side, or simply pulls up for the stroke, you shall cut in quickly and skillfully, using those cuts and techniques from which you can at once achieve a parry.
We know that cuts from Ochs are slow, as one has to unwind in preparation for an attack. But to take advantage of this you need to be in a position where you can attack directly without likewise performing a preparatory action. This could mean you could be in Tag with a cut, but a slice from Langort or Pflug is also viable.
In terms of measure, you need to be fairly close. Definitely within range of a passing step or there is no chance of getting there before the cut is completed. Ideally you are even closer than that, so at most all you’ll need is a small increase of the lead foot.