With a POD in 1500 this sounds really easy.
Maybe not as you think. If it was free from French rule, it would probably join in the unification if Italy.
Would Corsica be better off economically, if it gained independence? How much money does the island send to Paris, as opposed to the amount they receive?
So the easiest way is to simply keep it Independent is to have Britain put them under their protection and make it known to France that a war with Corsica is a war with Britain, which France would not want to purue at the time.
In the timeline that I'm working on Britain "lends" the Kingdom of Sardinia the money with which to buy-out the Genoese claim (just before the French purchase would have been agreed) on condition that Corsica is left as legally & effectively autonomous within that kingdom, leaning quietly on both Genoa and the Corsicans to accept this deal.It's unlikely that Britain would ever go to war with France on the sole cause of Corsica.
1)It's not as they already had many points in Mediterranea to secure their fleet.
2)Giving it openly their protection to what was legally and de facto a rebellion without real legitimity acknowledged in Europe would make them frown upon by every continental power.
It would make them fear that Britain could support every revolt as long they could have a slightest advantage on it.
Not the most interesting idea for keeping a functioning alliance system.
It's unlikely that Britain would ever go to war with France on the sole cause of Corsica.
1)It's not as they already had many points in Mediterranea to secure their fleet.
2)Giving it openly their protection to what was legally and de facto a rebellion without real legitimity acknowledged in Europe would make them frown upon by every continental power.
It would make them fear that Britain could support every revolt as long they could have a slightest advantage on it.
Not the most interesting idea for keeping a functioning alliance system.
I did'nt say going to war, I said threatening to go to war, which has been something that's wored for lots of countries throughout History.
Then there's two solutions.
1)France ignore. Britain withdraw and loose a great bunch of diplomatical credibility.
2)France complies (unlikely in my opinion, as they not only invested money but needed more than Britain to control the island), and Britain still enjoy the bad diplomatic effects listed above.
Britain was openly a backer of Corsica and its sponsor IOTL, I don't see why ensuring one of its allies remains independent would effect its diplomatic standing.
Because his ally happen to be revoltees. Every other power in Europe could logically deduce that Britain would find itself allowed to support every rebel that challenge their authority.
It wouldn't be anymore ensuring an ally, but supporting revoltess and being the bank of every troublemaker.
My point is the other European powers already knew Britain was doing so, so why would contionuing to do so change anything.
If France can support the American rebels why can't Britain support Corsican ones?