What could Napoleon have done to keep his Empire intact?

Question

We all know the story - General Bonaparte traipsed all over Europe's crowns until he tripped over Alexander's. Naturally the actual situation is much more complex than that. But the question remains - what could Napoleon have done to retain the First French Empire's 1812 borders? If that's impossible, how far back would we have to roll his conquests before they could be sustainable?

To clarify, I am not interested in other actors doing things differently. Yes, Napoleon would have won the Russian campaign if they had decided to surrender after losing Moscow. Yes, Napoleon would not have had to do the Russian campaign if Alexander had decided not to seek an alliance with Britain. I'm also not terribly concerned about Napoleon staying "in character."

I have a few starting points, but this is not my area of expertise, so please feel free to critique them:

• Refuse to invade Russia and permit the alliance with Britain. Napoleon has easily defeated four coalitions up to that point; a fifth was little threat to him.
• Finish the Peninsular War first. If the Grande Armée were committed entirely to Spain, he could have put an end to British and Portuguese ambitions, and then committed his entire army to fight Russia.
• Make a show of returning to the status quo. If the powers of Europe recognized him as just another monarch (rather than a dangerous revolutionary) they would be less inclined to try and bring him down.
• Use the carrot rather than the stick, and buy off the European powers. Britain was financing wars against
  France, but surely it is easier to take a small bribe and not go to
  war, than take a large bribe and have to go fight?
• March north to St. Petersburg and capture Alexander to force a surrender, rather than deal with Moscow. Avoid decisive battles until then by leaving just enough soldiers to keep Kutuzov busy, and rely on Baltic distaste for their Russian overlords to avoid guerrilla action.

Would some combination of these points, or some other things, make it possible to keep the Empire?

Answer 1

If his empire is much larger than France, he will have a problem with the British.

The basis of British strategy since the Norman Conquest has been "don't get invaded". The Roman conquest lasted 400+ years, and the Norman conquest has endured for 950 years. In both cases, the previous order of life and society in these islands ended with the conquest. So the British take being invaded much more seriously than the inhabitants of Belgium or Alsace-Loraine, and seek to prevent it.

As of Napoleon's time, a continental power in Europe has to have a large army to protect itself from invasion. For ordinary-size powers, that means they can't also afford a fleet large enough to defeat the British fleet, and make an invasion possible. However, if a power dominates all of Europe, it can afford a fleet large enough, in addition to the army it needs to defend itself against Asian powers. Because the British have historically spent most of their military budget on their Navy, they know they'll be conquered if their Navy is defeated.

So having any power dominate the whole or most of Europe is something the British really, really want to avoid in period, and they'll go to almost any lengths to avoid it.

Edit: The only thing Napoleon can do about this is to conquer everyone whom the British could ally with or exploit, and trying that was what caused his empire to fall. His having the economic power to build a big enough fleet and invade is a necessary part of being Emperor of Europe, and the British have a problem with anybody being able to do this.

Answer 2

Napoleonic wars were the continuation of the French revolution. Therefore, these wars were between the old and new order.

All monarchs saw France as a potential danger to them, in the same way as Russian revolution was a danger to other countries during the XX century. So I think the best parallel is indeed the Russian revolution. The Soviet Union didn't try to expand its influence beyond their frontiers and that helped them to survive, even though they were isolated.

While Napoleon, by extending his influence beyond France doomed the revolution. Because no prolongued peace was possible, only ceasefires thanks to his military talent. He was a virus that other monarchs must destroy in order to preserve themselves.

By 1812 no step back was possible. If any it would have been only another truce. He must defeat completely all other monarchs in order to preserve his empire.