In chapter 7, it begins by illustrating the despondency that animalism has brought upon them all. The setting is the bitter cold winter and the outlook is dismal. The windmill is in ruins and the animals have to rebuild it. The animals are working hard to rebuild it despite grumbling that they do not believe Snowball would do such a thing as destroy their windmill.
There is a rebellion staged by the hens who are angry that Napoleon wants hundreds of eggs each week to sell to humans.
What truly reveals the corruption of animalism is the culmination of the chapter and the climax of the book - the "purge." Napoleon forces and coerces confessions out of the animals and kills them in front of the rest of the animals. The graphic illustration of the blood across the floor and the tearing out of the throats is repulsive. There is enough imagery involved to disgust the reader into seeing corruption if the reader has been able to ignore smaller situations before this. The purge clearly violates the law that no one shall kill another animal, and it illustrates to the reader very emphatically that Napoleon is using fear to control the animals. It does not seem like an equality based society at all as promised from the beginning.
The animals buy into all the coerced confessions because the alternative is to live in terror of Napoleon who may randomly kill them at any time. By believing the lies and giving into the obvious facade of equality, the animals are able to find some sense of comfort and security.
The chapter ends with the new song by Minimus which does not even remotely inspire the animals as "Beasts of England" did and the focus of the song is on Napoleon. Again, equality is not emphasized in the piece but rather one animal who is more equal than all the others: Napoleon.