Napoleon took Moscow, and held it from 14 September to 19 October, 1812. I remember it like it was yesterday!
But it didn't do him any good. It was a mostly-deserted city with a horrible winter fast approaching.
So off he went, headed back to France again. A half-million French soldiers were lost during that little adventure, and most died horribly.
But your point is taken. War with Russia is no joke.