What happens in the Battle of the Cowshed in Animal Farm, and explain to me the building of the windmill? Chapters 4-7.
In the Battle of the Cowshed, a group of humans, led by the former owner of Manor Farm, Mr. Jones, attempted to retake the farm by force. But the animals were waiting for them. After a "light skirmishing manoeuvre" devised by Snowball,
... Snowball now launched his second line of attack. Muriel, Benjamin and all the sheep, with Snowball at the head of them, rushed forward and prodded and butted the men from every side...
The men seemed to have overcome this attack as well, and Snowball ordered a planned retreat. But other animals were "lying in ambush in the cowshed," and they attacked from the rear, denying the men an outlet to escape. Snowball ordered a full charge from the remaining animals, and soon the humans were in full retreat from the farm.
The windmill, conceived by Snowball in order to produce energy and ultimately reduce the workload on the animals, was scoffed at by Napoleon. However, after Snowball was run off the farm, Napoleon decided that the windmill would be constructed after all. It was a laborious task, since the animals had no hands and could use none of the humans' tools. The "animals worked like slaves" to complete the construction, and it took more than a year. A terrible windstorm left the windmill in ruins, but the animals began work again. The animals were forced to trade with the humans for grain and supplies, but the windmill was finally completed. Soon afterward, a group of humans blew up the windmill, but the animals again ran them off the farm in what became known as the Battle of the Windmill, and soon the animals once again began work on its ultimate completion.
Snowball had expected the humans to fight back to regain the farm, so he had been studying a book of Mr. Jones's on the battles of Julius Caesar. When the humans attacked, Snowball was ready. The animals were able to win what was later called the Battle of the Cowshed.
After that, Snowball, who had been studying some of Farmer Jones's manuals on electricity, began to advocate for building a windmill to generate electricity. He argued that in the long term a windmill would make the farm more productive. It would allow the animals to have hot and cold running water, a heater, and electric lighting in their stalls. Napoleon opposed building the windmill, saying their efforts should be put into increasing food production. He maintained that the animals might starve while constructing a windmill.
However, once Napoleon ran Snowball off the farm, he insisted that the windmill had been his idea all along and that he had simply pretended to oppose it. The animals built the windmill at great cost, only to have it fall down. They heard the humans say the walls were too thin, so, when they rebuilt it, the animals made the walls three feet thick instead of eighteen inches. Even though the humans then blew it up, the animals rebuilt it again. However, they never saw the promised benefits of it.