Funny how Napoleon remained remembered mostly for the good stuff he did - like reform of the French legal system and bureaucracy. A few million casualties - nah who cares, Napoleon is a cool dude.
Are you talking about the wars in which all of Europe attacked France for killing its king?
They may be talking about the subsequent wars, after Napoleon became a monarch himself.
He launched 2 invasions which were his greatest mistakes - Spain and Russia. But the rest, all 7 coalition wars, are the same: Europe scared that the idea of the people killing their king would spread, Britain first, and desperately trying to punish France. The European monarchies immediately forced France to restore the Bourbon kings both times they defeated Napoleon, makes it pretty clear what the whole point was.