What do they mean by the song Beasts of England and Ireland in chapter 1?

In Chapter One, Old Major relates his dream to the animals. His dream was about the state of happiness that will exist once Man is eliminated. In the dream, a tune his mother and the other sows sang to him in his childhood returned to him, and new words accompanied the tune. Old Major is sure that he has, in his dream life, uncovered an old animal anthem that has lain dormant for generations. It is called “Beasts of England,” and he sings it to the other animals. Orwell describes the song as “a stirring tune, something between Clementine and La Cucaracha” (32). The song glorifies the freedom and joy that will follow “Tyrant Man’s” overthrow, and he urges all animals to “toil for freedom’s sake,” even if they die before the cause is won.

The song rouses the animals, even the dullest of whom learn it in minutes. In fact, the animals are so taken with the song that they sing it five times in unison. The ruckus awakes Mr. Jones, who fires several bullets from his shotgun into the barn wall. The animals rush to their sleeping places, and the farm is silent once again.

Old Major represents Vladimir Lenin, the foremost author of the Russian Revolution and of the formation of the Soviet Union. If historically Marx played the role of grandfather theorist, then Lenin played that of young interpreter and motivator. Old Major not only bestows his theory upon the animals, he awakens them from the dreamtime of Man’s ideology and rouses them to action. He does so with the help of “Beasts of England,” a revolutionary song that helps the animals envision the “golden future time” when they will live free of man’s (literal and metaphorical) yoke. Orwell also connects Major to Lenin by his use of the word “comrade,” which is associated with communism.