Jean

"Only in 1813-14 did the inconvenient of the two-fronts war appear"

That is exactly what made the Peninsular War a major contributor to the defeat of Napoleon.

As I have already stated, take the Peninsular War out of the situation in Europe. How does history then play out?

Does Britain, cut-off from much of the regular trade, continue on? They were willing to discuss peace for a time in 1806. Would the Brazilian trade be enough? See Rory Muir's Britain and The Defeat of Napoleon 1807-1815.

Is there an 1809 for Austria?

Is there an 1812 for Russia?

What affect or influence might there be if all of those campaigners of 1805 to 1807 were available and not wasting, along with all those reinforcements, in the Peninsula? That leaves the French Empire with a large pool of men.

Still even Napoleon realized by late 1813 that he had to get out of Spain, if he was to survive.

Good hunting

Ron