There are many events in Animal Farm which help to define and further the plot. Due to the allegorical form of the novel (it is used to relate a far more telling story of the Russian Revolution), the significance of events has a two-fold effect.
Old Major's speech inspires the uprising as he identifies Man as the main cause for the animals' problems. The foundations of 'Animalism' and the Seven Commandments are created after his speech. He also teaches the animals "Beasts of England.':
Get rid of man, he says, and animals will be rich and free.
Slowly but surely, the pigs begin their rise to power. The 'milk and apples' is (are) set aside for the pigs, the 'brain workers.'Later on pigs are allowed to wear ribbons on their tails and the
piglets are kept separate from the other animals, enforcing the new elitism that continues to grow
The removal of Jessie and Bluebell's puppies is significant as they become Napoleon's 'security' and will be used to run Snowball off the farm.
The Battle of the Cowshed establishes Snowball as a hero
Animal Hero, First Class
but unfortunately it will be used later as a form of propaganda against him as Squealer tries to convince the other animals that Snowball was a traitor. Snowball's eviction is also a key event from which Squealer will feed in his attempts to turn the animals against Snowball.
Some of the animals confess to crimes against Napoleon and are executed. Significantly, the commandment has been changed:
No animal shall kill any other animal without cause
This is not the first time the commandments have been manipulated - the pigs get to sleep on beds - but no sheets! and later
No animal shall drink alcohol to excess
replaces the original commandment which did not include 'to excess.'Clover has noticed that all is not well but does not have the strength of character to do anything about it.
When Boxer, who steadfastedly believes Napoleon will do right by the animals
If Comrade Napoleon says it, it must be right
is sent away, having exceeded his usefulness
Squealer has an explanation for everything
thereby consolidating his position as propaganda boss, instrumental to the development of the propaganda theme.
At the end of the novel, the story has come full circle and the animals are confused and bewildered by what is before them:
The animals cannot tell the difference between man and pig. Both have been sublimated into each other.
For any more examples and explanations of events and characters, refer to the eNotes study guide and navigate to the character analyses and so on.