Please don't be an apologist for what happened. The Royalists made a threat of harsh punishment; in response, the revolutionaries executed tens of thousands of people, in many cases for little more than having more food than someone else.
It's strange. The defense of the Terror (and the brutal De-Christianization that came with it which was something that had never been seen in post-modern Europe) as something that was largely forced on France from outside forces is something even the Republic today rarely does. When it comes to Bonaparte - this reminds me of those (and they do exist) who think that the Duc D'Enghien got what he deserved and who buy Napoleon's public claim that it was Duke de Conde and Count de Artois' fault that this relatively harmless prince was kidnapped in a neutral state while on his honeymoon, given a show military show in the middle of the night and shot and dispatched in a grave already dug while the trial was going on - despite every historian of all stripes saying it was a mistake that turned European opinion against Bonaparte, despite Talleyrand and Fouche admitting it was a blunder, despite people in his court, including Josephine begging him to not do it, despite everyone involved like Hulin and Savary - everyone except Bonaparte - trying to disassociate themselves from the event after the fact. Bonaparte boasted of his role in the execution of D'Enghien in his will - so therefore there must have been a valid reason for it (other than to spread terror). It's always someone else's fault - the British, the royalists, disloyal marshals, etc.
From this point on, I'll no longer respond to people who want to argue whether or not these statements are true, because this isn't what the thread's about. Despite my attempts the Napoleon fanboys seem determined not to realize this, so the only appropriate response is silence. If anybody wants to dispute that the statement made by Blackfox5 is what the European powers thought about Napoleon, and that this belief would mean the seventh coalition would hold together beyond any initial defeats that Napoleon could hand out, then make your case and we'll discuss it.
Yes, there was no reason for anyone in the Coalition to back out in 1815. Anything to the contrary is Napoleon-wank. They had superior numbers, resources, almost all of them (particularly Prussia and Russia and Austria and Spain) had very personal reasons not only to loathe Bonaparte personally but reason not to trust him. France was no longer in the shape to be a conquerer and was just playing for time. Any victories it achieved even if Waterloo goes France's way would be pyrrhic. That's why I always consider the Hundred Days just an excercise in hubris on the part of Napoleon and his the French army (which still thought itself invincible).
Having declared him to the world publicly an outlaw and criminal, there was no way the Allied Coalition was going to let Bonaparte (who now had zero allies and no vassal states to get manpower and resources from) had burned too many bridges with his earlier behavior for them let him remain in power and rebuild the French army (which no one even now believes he wouldn't have eventually used at some later date).