Though the animals begin preparing for rebellion as soon as Old Major dies, they don’t know when exactly it is going to come. Yet we soon learn that "the Rebellion was achieved much earlier and more easily than anyone had expected" (2.10). What happens is that Mr. Jones goes out to get drunk and forgets to feed the animals. The cows are fed up and kick in the barn door, and all of a sudden all the animals are eating from the bins.
When Mr. Jones and his men come in to whip the animals into obedience, full-scale rebellion erupts, and the animals chase Mr. Jones and his men off the farm. Soon after, Napoleon and Snowball step into the lead and begin organizing the animals around a new system based on the Seven Commandments, the most important of which is that "All animals are equal" (2.21).
In this scenario, Mr. Jones is an allusion to the last tsar of Russia, Nicholas II. The tsars had been known for being out of touch with the Russian people for a long time, but Nicholas was a particularly bad case. In 1914, he got Russia entangled in World War I, and then mismanaged it. As a result of various blockages as a result of the war, a famine was beginning to creep across Russia (think of the farm animals not being fed). Nicholas, meanwhile, was not a strong enough leader to inspire the people’s confidence.
As we see in Animal Farm, the February Revolution was relatively unorganized, and seemed to spring up out of nowhere. It began with several strikes and demonstrations in St. Petersburg, which gradually grew in number. Nicholas eventually sent in the military, but by then the workers were out of control; many of the military members began to sympathize with the strikers and switched sides.
After the Revolution, Vladimir Lenin suddenly returned from exile and put up his April Theses (the ‘Seven Commandments’). A simple provisional government had been set up, but it was too weak to deal with the demands placed upon it. In October, the second phase of the Russian Revolution occurred when the Bolsheviks (the majority group of the different Russian communist parties) overthrew the provisional government.
Animal Farm aims to simplify these events so we don’t exactly get two rebellions, but we do get the pigs (the Bolsheviks) sweeping in to take control over the revolution that already happened. The one event that is notably glossed in the novel is when we hear that the animals "raced back to the farm buildings to wipe out the last traces of Jones’s hated reign" (1.13). In the novel, Jones and his family escape. However, after the October Revolution, Nicholas II and his family were executed and buried in a mass grave.