Les Miserables was written in 1862, so it couldn't take place in 1870 (Hugo didn't write stuff that took place in the future). Instead, it takes place over the course of some decades: first in 1815, and ends in 1832. It also contains the longest sentence in literature.
Oddly enough because of its anti-monarchy themes, I would have thought Nicholai would have objected to his daughter reading it... Guess I was wrong! That's very interesting... and hilarious about "merde" LOL!