In Animal Farm, what happens to the windmill the second time it was destroyed?

The toppling of the windmill the second time comes at the
hands of Mr. Frederick and his men. Previously, Animal Farm neighbors Frederick and
Pilkington were vying for the right to buy a stack of lumber from the
pigs.

The pigs went back and forth as to who they would
allow to buy the wood; getting the animals to first hate one neighbor and then the other
until they finally allowed Frederick to buy the
timber.

However, Frederick tricked the pigs by giving them
counterfeit bills in exchange for the lumber (probably because he was mad that the
animals jerked him around so much during negotiations). This was just the first step,
though, in  Frederick's revenge. He then showed up on the farm with backup and as part
of his attack on the farm, he placed dynamite at the base of the windmill and blew it
up.