Ulrich von Gradwitz and Georg Znaenym are enemies. So strong is his hatred that Von Gradwitz patrols his forest every night in the hope of accosting his enemy and killing him, a man he has detested since they were boys. It is only a bizarre act of nature that changes this relationship; without this intervention, the two men might have been able to kill each other.
That the men have long hated each other is evident from the beginning of the narrative:
...as boys they had thirsted for one another’s blood, as men each prayed that misfortune might fall on the other.
When von Gradwitz hunts his enemy one night, he comes face-to-face with him:
Each had a rifle in his hand, each had hate in his heart and murder uppermost in his mind....
But, before they can touch the triggers of their rifles ("[T]he chance had come to give full play to the passions of a lifetime"), nature intervenes as lightning strikes and the two are pinioned beneath the fallen mass of an old beech tree. As they lie helpless, von Gradwitz experiences a change of heart and charitably offers his flask to his enemy so that he can warm himself. He tells his old enemy that he has realized that they have been
"...rather fools; there are better things in life...than...a boundary dispute. Neighbour, if you will help me to bury the old quarrel I – I will ask you to be my friend.”
Ulrich then starts "feeling the old fierce hatred... dying down."
While the men do become friends before they die, without an aberrant act of nature that brings them together, they would probably have shot each other. So, perhaps a stronger argument can be made for their animosity for one another, rather than their friendship.