Politically, Napoleon divides the history of Europe in “before” and “after”. He grabbed the power in France after the Revolution with such skills that he had virtually no opposition. From there he conquered everything, from Egypt, to Russia and Spain. His fall was equally momentous. And then he did it again, leaving everyone confused and the political board of Europe forever reshuffled.
Victor Hugo is a man of that time, trying to make sense of all of this turmoil while mainly talking about people and their inner worlds. In Les Misérables he concentrated on the lowest of the low, poor people making bad choices.
At the time, it was believed that crimes had to be punished, but there was no hope for the criminal to be reinstated into society as a fully functioning member. Hugo makes the opposite claim: criminals are just good people in bad situations. And he talks about them.
While the length can scare readers off, I would encourage anyone to start it. Every page is a little masterpiece of human perception and empathy, with an author taking his time to fully build up not only stages but also souls.