How do Francois and Perrault respond when they discover that Buck has killed Sptiz? Why had the dog team become unruly?

Francois and Perrault weren't at all surpirsed by the battle or the outcome. They also seemed to welcome the end of the rivalry between the two, noting that without Spitz there wouldn't be anymore trouble.

"Eh? What I say? I speak true when I say dat Buck two devils."

This was Francois's speech next morning when he discovered Spitz missing and Buck covered with wounds. He drew him to the fire and by its light pointed them out.

"Dat Spitz fight like hell," said Perrault, as he surveyed the gaping rips and cuts.

"An' dat Buck fight like two hells," was Francois's answer. "And now we make good time. No more Spitz, no more trouble, sure."

The team became unruly because it lacked a leader.... until Buck stepped into that role.