The latest battle was named the "Battle of the Windmill". Although it was heralded as a victory, it came at a great price to the animals on the farm. The windmill, which the animals toiled in the hopes of a better life, was blown to bits. This seems to be symbolic of the animal's dreams of a better life when they rebelled against the humans.
The animals also must fight to ward off the attack, and manyof the animals are injured. Even Napoleon's tail is hurt in the battle. But the pigs need to spin the disaster into a tale of victory to try to keep the animals in check. The shambles that is left from the windmill's destruction is symbolic of the shambles of the dreams the animals had for a better life with no humans.