How does the conflict of Man v. Self appear in this story?

I think the outset of the story is man vs man. but the story concludes with nature having the final say. The two men plot revenge on one another but ultimately nature is the agent of revenge. This is partially because there are rules to be followed for human revenge. Though both men are armed when they meet, neither is free to shoot the other because of the “code of a restraining civilization” (392). Nature, under no such restraint, triumphs over these "interlopers" by acting quickly and decisively to subdue the men.