I don't know how to bite it

Hi, I'm translating a text about a historical figure Luis II. I got to the moment in which I'm blind. I do not really know how to bite it. Perhaps the phrase which I don't know is in German, but even in German it doesn't make sense for me. Please, help.
I this context below what's "am Recasch gen oven aus" in your opinion?
The Waywoda is said to have written
am Recasch gen oven aus

in the hope of becoming king [Louis]. It is to be feared
the Turk will gain possession of all Hungary, and make further aggression if not