According to squealer why was the gun fired after fredricks men were being chased away

Napoleon considers calling Pilkington for help, but Pilkington sends a note that says, “Serves you right.” As the animals watch helplessly, Frederick and his men blow up the windmill. After that, the animals put up a fight and manage to chase the men off. Squealer, who was not in the battle, has the gun fired as a sign of victory.