I'm starting an Tl and I need Britain to sit out of them for hopefully all of it but five to ten years is okay. Is it possible?
Boom22
Just to clarify do you mean out of the Napoleonic Wars or out of the Revolutionary and Napoleonic wars? Suspect you mean the latter but there is quite a difference.
May be able to keep Britain out of the Revolutionary wars, for quite a while if two things occur:
a) Louis XVI is not executed but a limited monarchy is established, possibly he is persuaded to abdicate in favour of his son, with a moderate regency. In which case you don't have the royal execution and bloodbath of the aristocrats that angers the British establishment. You would probably continue to have widespread public support of the revolution in Britain, albeit that the government and establishment will be keeping a careful eye on things. Down side of this is that you may have no revolutionary wars but possibly some clashes between the French government and the more reactionary continental monarchy that Britain decides are not in its interests.
b) For this you would need to have the French having only limited success and not getting radicalised by the conflict. If they start exporting the revolution or gain control of the Low Countries British attention will increase significantly and the government will turn against French interests. However could have some sort of fairly chaotic war that sees no one make big gains, especially in Belgium, but a fair amount of death and destruction. Possibly later on France starts to win big and Britain feels inclined to intervene. This may not be very effective for a while however as it will take some time and defeats to clear the deadwood from the system in the British army.
To get a situation where a Napoleonic France has the Rhineland and becomes a friend/ally to Britain in the 1820's you will need a radically different Napoleon. Possibly the limited monarchy in France ultimately fails and Napoleon is the successful military commander who rescues it, but without becoming a self-proclaimed emperor and despot in his own right. Might be able to have him more moderate without the power going to his head. Possibly, although difficult with a Borbon monarchy would be to have him married into it and assume power that way. That would be a lot less antagonistic to the other royal dynasties but you would need to have him willing to accept a limited success of France retaining its territory and making some small gains, say in the Rhineland, without seeking to dominant Europe totally.
One other problem with a prolonged period of conflict in Europe without Britain involved is where are the funds coming from. France largely funded its empire by conquest and loot whereas the allies were generally depended on considerable funds from Britain. With a more moderate and financially exhausted France that isn't basing its army on occupied territory [since its not seeing the dramatic successes of OTL] and their opponents not having British funds it could be a very stop-start conflict with much smaller forces involved.
Steve