The historical context of Orwell's work is based on the struggle for political identity that emerged during the Russian Revolution. Consider Orwell's own words on this point:
I thought of exposing the Soviet myth in a story that could be easily understood by almost anyone and which could be easily translated into other languages.
For Orwell, displaying the manner in which power was seized in Russia became the driving force. The fact that Orwell was living on a farm at the time of writing and he sought to make the narrative understandable to anyone compelled him to make the animals the central focus of the work. Napoleon parallels Stalin in that both become the inheritors of power of a revolution. Both leaders assume or take power from the original call for change and must sustain its drive. Both leaders do so by continuing the call for change, but actually become more interested with consolidating their own power. Finally, I think that both Napoleon and Stalin are similar in that their defining element is the fact that they were willing to maintain and hold power no matter what. The calls for revolution and appeal to the public for initiating change were merely veils for keeping and maintaining their own power, representing the idea that "with power comes corruption."