What threats did Ulrich von Gladwitz and Georg Znaeym make to one another?

Georg:

“Are you sure that your men will find much to release? I have men, too, in the forest tonight, close behind me, and they will be here first and do the releasing. When they drag me out from under these branches, it won’t need much clumsiness on their part to roll this mass of trunk right over on the top of you. Your men will find you dead under a fallen beech tree. For form’s sake I shall send my condolences to your family.”

“Good,” snarled Georg, “good. We fight this quarrel out to the death, you and I and our foresters, with no cursed interlopers to come between us. Death and damnation to you, Ulrich von Gradwitz.”

Ulrich:

“It is a useful hint,” said Ulrich fiercely. “My men had orders to follow in ten minutes’ time, seven of which must have gone by already, and when they get me out—I will remember the hint. Only as you will have met your death poaching on my lands, I don’t think I can decently send any message of condolence to your family.”