After Snowball is driven from the farm in Animal Farm, the weekly meetings are disbanded. From here, the changes begin increasing in number over a period of time. It is in part due to the gradualism of the changes that no one on the farm protests- it happens little by little. Another reason for the lack of the protest is that Napoleon has his own army in the now-grown puppies.
Soon, Napoleon takes credit for the windmill that he so despised that he urinated on Snowball's drawn plans of it. Later, he orders propaganda minister Squealer to begin changing the commandments and orders executions. Shortly after this, Clover the mare begins singing "Beasts Of England" to comfort herself and others only to learn that the farm anthem has been outlawed.
The changes Napoleon makes after expulsion are too numerous to list, but this is an example of some of the most glaring ones.