The windmill originally collapsed in November, when "raging south-west winds" tumbled its walls, leaving it in ruins. The destruction of the windmill was not blamed on the weather, but on Snowball. The animals quickly began rebuilding during the "bitter winter." The following spring brought the news that "Snowball was secretly frequenting the farm by night!" "Four days later," Napoleon ordered executions by those animals believed to be collaborating with Snowball.
Throughout the year the animals worked even harder than they had worked in the previous year.
Although the machinery still had to be purchased and installed, the windmill was finally completed
... in the autumn, by a tremendous, exhausting effort...
"Two days later," the animals were notified that the lumber had been sold to Frederick. Soon, the timber was delivered, and "three days later" it was discovered that "the bank-notes were forgeries!"
The very next morning the attack came...
and the windmill was blown up by Frederick and his men. Although no specific date is given, it came during the autumn (fall) season.