During the Battle of the Cowshed, Snowball, one of the co-founders of the Animal Revolution, turns back an attempt made by Jones and his fellow farmers to take back the farm. Snowball studies the tactics of Julius Caesar and organizes the animals so that the battle turns into a rout of the humans. Boxer is in the front, fighting alongside Snowball. Boxer also kicks a young farmhand in the head, but only stuns him. Snowball and Boxer are awarded medals and the Battle of the Cowshed is marked as a major holiday in the history of Animal Farm. Napoleon, the other leader of the revolution, is nowhere to be seen during the battle, but in the retelling he appears prominently, even fighting the forces led by the "traitor" Snowball.
My advice for you, as you are telling this from the animals' point of view: remember, your view will be limited. Most of the narration of Animal Farm is done by an omnipotent narrator who can see the entire battlefield. You do not have that luxury, unless you are Moses the Raven, but it's not even likely he was there that day. Put some information about Snowball and Boxer into your work, and you may even show remorse for the dead sheep, but remember: you are an animal who is providing a witness for the paper, and you have no knowledge of how the battle will be retold historically.
The basic answer to your question is that, under Snowball's leadership, the animals are able to defeat an attack by the humans. They are attacked by Mr. Pilkington and Mr. Frederick, whose animals have become "unruly" when their animals heard of the rebellion. So, even though they don't usually get along, Pilkington and Frederick join forces and attack Animal Farm. Snowball has read a book about Julius Caesar and his military tactics so he organizes the battle and the animals win. The complete details of the battle are located in Chapter 4 of the novel. In the end, Snowball and Boxer are awarded the military decoration of "Animal Hero, First Class." Only one sheep is killed and it is awarded the distinction of 'Animal Hero, Second Class."