From The Third Book: Lines 29-30 of Meyer’s Zettel:
See that you are the first on the field; before your opponent adopts a posture, lay on against him.
Master Meyer explains further:
“… so that you can act in a timely manner in your intended stücken; then you shall be so persistent against him with cuts and steps that he can have neither time nor space to choose a posture or stück, and you shall thus rush upon him with sudden steps before he realizes it.” – Meyer (1570) “Grundtliche Beschreibung der Kunst des Fechtens”, 1.45v
Meyer is talking about seizing and maintaining the Vor.
Meyer speaks further of the Vor, that is the act of having the initiative.
“The Vor is when you drive with your stücken so that he cannot come to his senses, especially by positioning yourself close, and how he defends before your stücken and these same would like to break and bar, with this, he runs off the Vor to you.” – Meyer (1560) MS A.4o.2, 1.6r
“It is called Vor when you attack your opponent with your cutting first in the Zufechten , and further drive on, so that he cannot come to his undertaking or stücken, but must restrict himself to parrying so that he may defend himself from you.” – Meyer (1570) “Grundtliche Beschreibung der Kunst des Fechtens”, 1.24r
More on Vor from those predating Meyer in the Kunst des Fechten:
“With the word Vor as has been told before, he [Liechtenauer] means that you, with a good Vorschlag, shall close in without fear or hesitation and strike at the Blossen; to the head and to the body, regardless whether you hit or miss you will confuse the opponent and put fear into him, so that the he does not know what to do against you. Then before the opponent can gather himself and come back, you shall do the Nachschlag so that he will have to defend yet again and not be able to strike himself.” – Anonymous (1389)
“Vor” means, preempting him with a blow or a thrust against an Blossen before he can hit you, so he must defend/displace. So, be flexible in your defense and aim with your sword at one opening after the other, so he cannot get through with his own techniques.” – Ringeck (MS Dresd.C.487; 15v
“What the Vor is that is that you shall always come before, be it with the strike or with the stab, as when you come to him with a strike or otherwise so that he must displace you, Indes, work ahead nimbly with the sword in the displacement or else with other parts, that he can come to no work.” – Anonymous “Pseudo-Peter von Danzig” (pre 1452)
A bit from Mike:
“He who maintains the initiative forces the opponent to react to defend themselves giving up the control of the fight to the man in the Vor. The German school often advocates a flurry of strikes (Meyer mentions four strikes as his preferred combination number) to gain and deftly exploit the Vor, keeping up a relentless pressure of attacks to limit the opponents ability to counter.” – Cartier (2005) “The Art and Practice of Longsword Combat according to Joachim Meyer, Free Fencer” pg 20