In this scene, Mr. Jones the old drunken farmer is abusing one of his pigs, and the other animals are very mad because they adore this pig they look up to him.
Poor animals, Napoleon is a lying jerk.
The animals are mad at the farmers, so they went after the humans on a attack and started hurting them to the point where the humans left the farm running.
The battle of the cowshed is when the humans came back to the farm to try and gain it back again, but the animals were waiting there with a plan to attack. The animals won.
Napoleon chased snowball off the farm, because he was a threat to his power. He took over all the power of the farm and took advantage of the animals and their education abilities. He changed the rules of the farms and is doing human like things. He is taking advantage of the animals. Also, the windmill they all built, got knocked down by the wind.
The humans came back to fight and ended up blowing up the animals windmill. Also Boxer had gotten shot and got very injured so they called the "Hospital" although it was really a slaughter house. The animals chased after the car with Boxer in it, getting taken to his death, while Napoleon said he's going to the hospital, although he knew he wasn't but Napoleon was getting paid for Boxers death to buy more whisky.
No, he's just going to the hospital
BOXER! N0 YOUR GOING TO YOUR DEATH!
The pigs have officially taken control. the animals gaze outside the farmhouse to see pigs and the humans sitting at a table drinking beer, wearing Mr. Jones clothes, and playing cards. And both the humans and pigs placed down a ace of spades, which means one has cheated. The animals couldn't even tell them apart. And now the "Animal Farm" has gone back to "Manor Farm".