The first harvest under animal management, the reading and writing campaign, the pigs' assumption of privilege, and Napoleon taking the puppies.
The hay harvest is brought in by every animal on the farm, including the ducks and hens. The pigs, being too clever to work with tools that require standing on two legs, take supervisory roles instead. Boxer and Clover, knowing the intricacies of horse-work, provide most of the practical expertise. The harvest is completed faster than Jones ever managed it, and it is bigger than any previous harvest. The animals eat it themselves. There is no one to hand it to.
During the summer, everything goes well. There are difficulties -- threshing the corn without a threshing machine, for instance -- but the pigs are clever enough to work around them, and Boxer is strong enough to pull the farm through. Boxer rises half an hour before anyone else and works wherever he is most needed. His motto is "I will work harder." Mollie and the cat perform as little work as possible.
Benjamin is unchanged. He works at the same pace as before, neither better nor worse. When asked whether things are better without Jones, he says only that donkeys live a long time and that none of them has seen a dead donkey.
On Sundays there is no work. The animals hoist a flag: a green field with a white hoof and horn painted on it by Snowball (the green representing the fields, the hoof and horn representing the future Republic of the Animals). Sunday morning assemblies are held in the barn to decide the week's work, with the pigs the only ones proposing resolutions. Napoleon and Snowball are the most active debaters and never agree on anything.
Snowball organises several committees: the Egg Production Committee, the Clean Tails League, the Wild Comrades' Re-education Committee (for taming wild animals). All fail. His one success is the reading and writing campaign. By autumn, every pig can read and write well. The dogs learn to read but choose to read only the Seven Commandments. Muriel, the goat, reads reasonably well and reads newspapers aloud when she can find them. Benjamin is completely literate but refuses to use this ability. Clover learns the whole alphabet but cannot put the letters into words. Boxer can never get beyond the letter D. Mollie learns only how to spell her own name, written in flowers.
For animals who cannot master the Seven Commandments, Snowball reduces them to a single maxim: "Four legs good, two legs bad." He explains to the birds that wings count as legs for this purpose. The sheep take to repeating the maxim for hours on end.
Meanwhile, the pigs claim all the milk and windfallen apples for themselves. Squealer explains that this is not selfishness: pigs are brainworkers, and the milk and apples contain substances (brain food, he says) necessary for them to manage the farm. Without the pigs' management, Jones would come back. "Surely, comrades, you do not want Jones to come back?" The animals see his point.
Napoleon, who has shown little interest in educational programmes, takes an interest in the nine puppies born to the dogs Jessie and Bluebell. He takes them away to the loft above the harness room, saying he will see to their education himself. The other animals soon forget about the puppies.
The chapter is deceptively cheerful. The harvest is a genuine success and the animals' pride is genuine. But Orwell has already introduced the structural elements that will undermine everything: the pigs' supervisory roles, the differential in literacy, the milk and apples, and Napoleon quietly withdrawing nine puppies from the community.
The dogs' literacy is a fine detail: they learn to read but choose to read only the Seven Commandments. They are not educating themselves; they are training themselves to know the rules. This anticipates their function as enforcers in Chapter 5.
The maxim "Four legs good, two legs bad" is Orwell's first precise illustration of how complex ideas become slogans. Snowball reduces the Seven Commandments to this phrase for animals who cannot manage more. It is a genuine compression: the principle is sound as far as it goes. But a slogan cannot carry nuance, cannot be verified against reality, and can be changed by whoever controls the language. In Chapter 10, the sheep will chant "Four legs good, two legs better" without noticing the contradiction.
Squealer's first significant speech, justifying the milk and apples, establishes the template for every subsequent intervention. The argument structure is: pigs need this because of special circumstances; the alternative is Jones; surely you do not want Jones to come back. The argument is unanswerable from the animals' position. They cannot verify the biology; they cannot disprove the threat; they cannot see an alternative. And so they accept. The pattern repeats in every subsequent chapter with escalating stakes.
Napoleon's removal of the puppies is the chapter's most important single action, and it is described in one sentence. No one questions it. No one thinks about it again. It is the most significant thing that happens in the chapter.