Fair enough. So what international conventions?
The conventions European nations had been following since about the end of the 30 years war. Civilians were not deliberately targeted. Capture soldiers were accorded honorable treatment etc.
Really? And about six years after the end of the Southern Rebellion when Prussia invaded France, laid siege to Paris and bombarded it? Did they forget that they weren't supposed to do that since the 30 Years War? Or did they just make an exception?