Much can indicate that the climax of Incident at Hawk's Hill is the confrontation between between William and Burton. While William has wanted to be accepted by Ben and has sought to try to accept Ben, there has always been a barrier between them. Ben's own condition of not being able to outwardly generate emotion and William's awkwardness at trying to understand someone who is challenging to understand have contributed to this. When Ben returns with the badger, there is an even greater awkwardness as Ben straddles two worlds. Ben gives the world of humans and of badger equal weight, making communication with William an even greater challenge.
When Burton appears at the end of the novel to kill the mother badger, almost seeking to finish what he began with the badger population in general, it becomes a critical moment for the relationship between father and son. If William sides with Burton, he will sever the bonds between he and his son. There is little to indicate that Ben would ever forgive his father for A) Betraying his surrogate mother in the badger and B) Siding with Burton, who Ben feels is the personification of evil. Given how Ben battled against Burton's dog and assumed the badger's persona against a man like Burton and his dog, this conflict is the critical point in the novel. It is the climax in terms of the emotional dynamic between father and son. It is also the climax in terms of deciding the fate of the badger herself, one who has endured an already challenging amount of struggle throughout the narrative.
When William faces Burton down and rejects him through force and will, it represents the moment in which father and son can reconcile. The awkwardness and distance between both is overcome in this instant. One can see the emotional impact this has in how Ben communicates with his father: "If she . . . dies . . . would you help me bury her, Dad?" Such a reconciliation comes about because Ben sees his father siding against the personification of evil and embracing Ben's side in the struggle. The ending of the book confirms this. Ben weeps into his father's arms and embraces him "so fiercely . . . that it almost cut off his father's breath, but William MacDonald didn't mind. Not at all." This ending is one of unity. It is only evident because of the final struggle between William and Burton. For this reason, the final conflict between both men can be seen as the climax of the novel.