Why are Georg and Ulrich fighting?

In H.H. Munro's short story "The Interlopers," the two antagonists are inheritors of a generations-old feud over land. Specifically, Munro, writing under the pseudonym "Saki," places his story in a strip of forested land along the Carpathian mountains that is rich with game. Two neighboring clans or families, the Gradwitz (Ulrich's family) and the Znaeym (Georg's family) have feuded for years over proper ownership and exploitation of this land. Early in his story, Munro references "a famous law suit" between the two families over ownership of the land in which Ulrich's family prevailed. As "The Interlopers" begins, Ulrich von Gradwitz is patrolling this land, watching for any members of the Znaeym family who may be poaching game. This is a blood feud, and violence is an integral part of the relationship between the two groups.
As readers of "The Interlopers" know, the two reigning patriarchs of their respective clans are pinned to the forest floor by a large tree that falls on them and that, during their ordeal, they agree to put aside the feud and make peace. Their plans for a cordial relationship, however, are dashed when they are presumed eaten by a pack of wolves.