Buck's beastly nature steadily grows, though he makes not sign to betray it to the others. He picks no fights, concentrating solely on getting through each day as best he can. Sensing a rival, Spitz never misses an opportunity to remind Buck of his place. Many times he attempts to start a fight that must end in one of their deaths. Buck resists his growing dislike of Spitz until one particularly difficult and cold night, Spitz takes over Buck's nest while he has gone to eat his ration. Furious, Buck leaps at Spitz. Francois discerns the cause of the argument, and cheers on Buck. Suddenly everyone realizes that four of five starving huskies have invaded the camp.
They pounce on the food, crazed by its smell. The team has never seen such dogs. Gaunt skeletons with eyes and fangs. The strange huskies attack, and Buck finds himself viciously fighting for his life. Just as he kills two of the huskies. Spitz treacherously attacks Buck from the side. Buck shakes him off and concentrates on driving off the strange dogs. The men are forced to concentrate on defending the food. The team takes flight into the forest, where they regroup to return to camp. All are terribly wounded, and the sled harness is a mess, having been chewed in various places. Half of tehir food is gone.
Despite these hindrances, the team sets out on the toughest part of the trail. Francois is worried that the dogs will develop madness because of their wounds, but Perrault refuses to coddle them. It takes 6 days for them to travel thirty miles. Occasionally they break through the ice, and the dogs have to be thawed by a fire. Perrault is relentless. He cannot be daunted, and wants to clear the 400 miles to Dawson as soon as possible. Several times the sled is almost dragged under the ice, but each time Perrault manages to get them over the next crest.
Buck's feet give him trouble, for they have softened in the generations since his ancestors roamed the forests. Francois makes buck four moccasins, which he uses until his feet grow tough, and they are thrown away. One of the newest dogs, Dolly, becomes mad and attacks Buck. Buck flees and eventually races back, relying on Francois to save him. Francois kills Dolly with an axe, and Buck collapses, exhausted. Spitz takes advantage of this moment of weakness and attacks. He is driven off by Francois who administers a severe lashing. Perrault believes that Spitz is going to kill Buck, but Francois insists that it is Spitz who should be afraid.
Everyone seems to know that the fight is drawing nearer. Buck wants it. He craves it because it is in his nature. Like the others, he has learned the pride of toil, and this pride threatens Spitz. He interferes when Spitz disciplines other dogs. He cares more about undermining Spitz than anything, and once he is soundly punished by Francois for protecting a malingerer from Spitz's punishment. The solidarity of the group is destroyed by Buck's clever undermining of Spitz's authority. The team arrives at Dawson, and Buck marvels at the sight of the dogs, everywhere working. He meets a few dogs like himself, dogs from the Southland, but most are wild huskies. Each night the dogs howl together, singing an ancient song which "harked back through the ages of fire and roof."
A week later the team leaves Dawson. Perrault is carrying urgent dispatches and he is determined to set a record. They travel speedily and well, but Francois must work extremely hard keeping order. Spit's authority has been destroyed, and constant petty fights must be whipped off. One night the dogs spot a rabbit, and they chase after it, joined by a nearby pack of fifty police dogs. Buck, leading the pack, rejoices in the hunt, all of his instincts overwhelming him. Spitz, cold and calculating, takes a different route to head off Buck before he can reach the rabbit. Spitz jumps upon the rabbit, and without thinking Buck leaps upon him. He knows that their time has come. This is a fight to the death. At first Spitz clearly betters Buck. After a few moments Buck is covered in blood, while Spitz is untouched. Spitz is an experienced fighter, but Buck possesses imagination. He tricks his rival, and is able to break both forelegs. Spitz is beaten. Buck knows that this is no place for mercy. He knocks Spitz onto his back and the sixty dogs rush in to finish him off.
In this section of the novel, Buck comes into his own. When we first met Buck, at the Judge's home, he is benign and mild-mannered, lacking in any real character. As Buck's wildness grows, he reveals his character to the reader. He is sneaky, subtle and intelligent. He desires dominance, but he knows better than to seek it out until the right moment. Buck not only instinctively sees means for survival, he exploits his understanding of the other dogs and their human leaders.
The forced equality of dogs and men also grows clearer. Though in town men have the ultimate control, on the trail the team and its leaders are interdependent. Once again, the reader sees the savage loyalty which must exist in order for the group to survive. Each time man or dog breaks trough the ice, they must work together in order to survive. They are literally and figuratively yolked together.
It is logical that Buck's self-control starts to break when Spitz occupies his sleeping nest. Buck cannot tolerate Spitz's invasion, because to do so would be to signal his total submission to Spitz. It is not a matter of pride, but literally of survival. London points out that in the civilized world, Buck would have had the luxury of fighting for foolish reasons - to protect the Judge's "riding crop." In this world, Buck can never risk a fight unless their is no way to avoid it. He must fight solely to survive. Thus, when Spitz and Buck first engage in a real fight, but are interrupted by the attack of the wild Huskies, Buck immediately shifts his focus. The survival of the team must take priority over his personal struggle with Spitz. Spitz reveals a fundamental weakness when he treacherously attacks Buck. Spitz becomes a threat to the team because he puts his own desires above the team's need. London subtly and masterfully establishes the reader's preference for Buck. This preference is cemented during this fight, as one cannot help but be struck by Buck's greatness.
London emphasizes the team's interdependence and group existence with the manner in which Spitz and Buck's fighting disrupts the group. The dogs human tendencies are emphasized as Buck and Spitz battle for power. Like a clever politician, Buck gains support by backing up the weakest members of the team. Once again power and loyalty are seen in conflict. Despite Buck's native understanding of the need for teamwork for survival, he knows that he will not survive unless he challenges and eventually overpowers Spitz.
The rabbit that precipitates the long-awaited fight inspires in Buck "blood lust" and "the joy to kill." in some ways Buck has become more like Spitz, for the idea of killing is no longer foreign to him. Buck's joy for the chase, and especially for leading the chase, signals his readiness to defeat Spitz. The tone of London's prose becomes more frantic as the two roll in the snow. Significantly, it is Buck's imagination, not his greater instinct, which allows him to kill Buck. This idea is different than that advanced thus far in the novel. Before London emphasized the importance of instinct over reason, and the greater happiness of the dog that harkens back to instinct. Now London suggests that Buck is superior to the other dogs because of a combination of instinct and human-like intelligence. The fact that he is on more of a human wavelength gives him an advantage over most other dogs.
While London suggests there is an advantage for dogs in learning from humans, London also implies that humans are less different from animals than they might like to admit. London suggests that the human desire for the hunt and their instinct to kill is inseparable from an animal's. Human's do not kill out of reason and thought any more than dogs do, but are similarly caught up in bloodlust and thrill of the chase. In the world of the gold rush, men and dogs grow more alike. Their wilder natures are awakened, and they are bound together by 'animal' desires to survive and conquer the 'inhuman' landscape.