He also deals mercilessly with the hens when they go on strike and there is the mass slaughter of the animals in the barn.
He sends Boxer to be killed and not to the hospital - the ultimate betrayal since Boxer had shown unflinching loyalty to napoleon.
He becomes a recluse and when he does appear in public he is announced by a cockerel and surrounded by dogs.
In chapter 5, Napoleon asserts his authority by running Snowball off the farm with the assistance of the dogs he had been training from birth to be his brute squad. He then cruelly, but persuasively, announces that he is the leader, and that he has authorized the pigs to make all decisions from here on out. Of course he uses techniques of propaganda to help the rest of the animals think this is fair. He demoralizes the animals keeping his dictatorship in effect by using the force of the dogs.
In chapter 6, Napoleon's hypocrisy to the commandments begins to surface. We as readers see that the rules apply to the animals, but not him. For example, he trades with neighboring farms which makes all of the animals on this farm work even harder and more. He also hires a human. Thus, Napleon can deal with two legs, even though they are bad.
In chapter 7, conditions on the farm grow worse. The winter begins to really hurt the farm and rations are cut to almost nothing. In an effort to continue to raise money, Napoleon demands that the hens eggs also be sold. Hens die as a result of Napoleon's strict and demoralizing leadership.
I hope these ideas help you prepare.