I have only read the first two chapters but I am detecting an anti war sentiment in Hugo's writing. Hugo is describing carnage and destruction. I see no trace of sentimentality in his observations. Nearly everything described here, from doors to wells, has been altered by war. I really like Hugo's summary at the end of the seocnd chapter:
"Bauduin, killed, Foy wounded, conflagration, massacre, carnage, a rivulet formed of English blood, French blood, German blood mingled in fury, a well crammed with corpses, the regiment of Nassau and the regiment of Brunswick destroyed, Duplat killed, Blackmann killed, the English Guards mutilated, twenty French battalions, besides the forty from Reille's corps, decimated, three thousand men in that hovel of Hougomont alone cut down, slashed to pieces, shot, burned, with their throats cut,--and all this so that a peasant can say to-day to the traveller: Monsieur, give me three francs, and if you like, I will explain to you the affair of Waterloo!"
In a sense Hugo is asking what did all the killing really achieve? A bit of tourism? If Hugo had lived to see the First World War he would have been utterly appalled by it.
I do not really get the criticism by some people that the Waterloo section was about downplaying the victory of the UK. Maybe I will change my mind after reading more.