Answer:
The main opponents of Napoleon was Britain, and later joined by Austrio-Hungary, Germany, the Russian Empire, and many other smaller nations.
These countries felt a need to oppose France under Napoleon, for they themselves had monarch governments, and on seeing the French Revolution that led to the capitulation of the Royal government and civil unrest, which led to the rise of (what they thought) was a fanatical Bonaparte, they believed that, if their own people took a hold of the ways of the French, that they themselves would be thrown out of power. This led to the governments of these other nations to band together to throw Bonaparte out and reinstate the royal family to re-balance the royal structure in Europe.
~
Austria Hungary, Germany, Bulgaria and the Ottoman Empire were part of the central powers in WW1.
The two warring classes of The Communist Manifesto are the bourgeoisie - the capitalists, or the owners of the means of production and the working class, called the proletariat, which works for wages and does not (directly or personally) own the company they work for.
