While fighting alongside Fred against Napoleon, there's music playing that seems like a part of a classical composition. What's its name? Has it been composed for the game or is it part of a previous work?
The name of the song is "Napoleon's Final Conflict Revisited."
It has taken parts from Tchaikovsky's 1812 Overture hence the classical composition, so in fact has been both composed for this game a bit as well as being part of a previous work.
You can find the music for the video here which also tells you all about the piece in the description: