Read the passage from chapter 7 of Animal Farm. If she [Clover] could have spoken her thoughts, it would have been to say that this was not what they had aimed at when they had set themselves years ago to work for the overthrow of the human race. These scenes of terror and slaughter were not what they had looked forward to on that night when old Major first stirred them to rebellion. If she herself had had any picture of the future, it had been of a society of animals set free from hunger and the whip, all equal, each working according to his capacity, the strong protecting the weak, as she had protected the lost brood of ducklings with her foreleg on the night of Major's speech. Instead—she did not know why—they had come to a time when no one dared speak his mind, when fierce, growling dogs roamed everywhere, and when you had to watch your comrades torn to pieces after confessing to shocking crimes.

Which historical circumstance most likely influenced the writing of this passage?