How is the windmill destroyed? why does napoleon blame snowball? in animal farm?

Boxer, in particular, commits himself to Animal Farm, doing the work of three horses but never complaining. Even though the farm possesses all of the necessary materials to build the windmill, the project presents a number of difficulties. The animals struggle over how to break the available stone into manageable sizes for building without picks and crowbars, which they are unable to use. They finally solve the problem by learning to raise and then drop big stones into the quarry, smashing them into usable chunks. By late summer, the animals have enough broken stone to begin construction.

Although their work is strenuous, the animals suffer no more than they had under Mr. Jones. They have enough to eat and can maintain the farm grounds easily now that humans no longer come to cart off and sell the fruits of their labor. But the farm still needs a number of items that it cannot produce on its own, such as iron, nails, and paraffin oil animals work at a backbreaking pace to farm enough food for themselves and to build the windmill. The leadership cuts the rations—Squealer explains that they have simply “readjusted” them—and the animals receive no food at all unless they work on Sunday afternoons. But because they believe what the leadership tells them—that they are working for their own good now, not for Mr. Jones’s—they are eager to take on the extra labor. I HOPE THIS HELPS