The Call of the Wild by Jack London tells the story of Buck, a dog living a pampered life in the Santa Clara Valley who is abruptly kidnapped and sold to toil as a sled dog in the frozen north during the Klondike gold rush. Buck and Curly, described as "a good-natured Newfoundland," are bought by two men named Francois and Perrault.
When they reach the beach where they disembark from the ship, Buck recognizes that the men and dogs are unlike any he has ever encountered. "They were savages, all of them, who knew no law but the law of club and fang." Friendly Curly approaches a wolf-like dog that is much smaller than she is, but without warning it attacks her. Her opponent strikes, slashes, and leaps away, inflicting wounds, but the decisive moment is when it knocks her off her feet. The surrounding huskies then rush in and rip her apart. After Curly's violent death, London writes,
The scene often came back to Buck to trouble him in his sleep. So that was the way. No fair play. Once down, that was the end of you. Well, he would see to it that he never went down.
So, the death of Curly teaches Buck that in fights with other dogs, he can expect no fair play, and he needs to always stay on his feet. If he doesn't, the other dogs will tear him apart like they did Curly. These lessons are crucial to his survival and eventual victory when he later battles Spitz, the lead dog.