explain how and why the rebellion occurs. what were the immediate and long-term causes?

Old Major calls for the rebellion after having a dream. He tells the animals that it's time for them to rise up against Farmer Jones and create their own farm...... their own Utopia.

Stirred by the belief of what could be, the animals rise up against Farmer Jones and drive him from the farm. No loss there, he was a cruel taskmaster. Unfortunately, as time goes on the animals are forced to serve other masters.... maybe even more cruel than the first.