In Animal Farm, what makes the Battle of the Windmill against Frederick's men seem different from the Battle of Cowshed?
The spirit of the animals has grown grimmer and more despondent since the early days of the Battle of Cowshed. The animals have had to build the windmill twice, since the first time it fell down, and the loyal Clover has to mask her discontent by singing the "Beasts of England" song when it occurs to her that a regime of hard toil and public executions was not what she had envisioned when the animals first dreamed of owning the farm. Right before the battle, Napoleon sold their timber to humans for cash, an act violating the principles of animalism. By the time of the Battle of the Windmill, the animals are tired and the early euphoria of their revolt has worn off. Napoleon's only plan for defense, apparently, is to hope Pilkington and his men will help them out, but Pilkington instead sends him a note saying "serves you right." The animals are routed, retreating to farm buildings, until the humans dynamite the windmill. That act rouses them to fury and they then drive the humans out. A difference showing how attitudes have hardened is revealed when Boxer deliberately breaks the heads of three humans with his hoofs and doesn't mourn this, whereas he had been distressed when he accidentally killed a farmhand in the long-ago Battle of Cowshed. The animals instinctively know they have lost this later battle because of the destruction of the windmill. Even Boxer, realizing he is 11 and not as young as he used to be, wonders if his muscles have what it takes to rebuild. (He nevertheless "braced himself for the task.") When Squealer announces the battle a great victory and Napoleon orders a celebration, however, the animals succumb to the propaganda and begin to change their thoughts.
The two battles in Animal Farm were much different. At the Battle of the Cowshed, Snowball had devised a brilliant battle plan that called for a deliberate retreat, counterattacks and diversionary tactics. The humans were taken by surprise, and the animal victory came easily and with few casualties. The Battle of the Windmill was far different: Although the animals knew an attack was imminent, Napoleon had not devised a battle plan. When the men showed up in larger force and with many guns, they opened fire and the animals hid in terror. It was only the explosion which destroyed the windmill that fueled the animals' anger, causing them to make an all-out attack on the men. They faced the guns bravely this time, and despite many casualties--
A cow, three sheep, and two geese were killed, and nearly everyone was wounded...
the animals again chased the humans from the farm. Although Squealer proclaimed it a victory (and technically it was), even Boxer questioned the announcement.
"... they have destroyed the windmill. And we had worked on it for two years!"