I'm surprised that no one has mentioned the French War against America.
After the end of the "French and Indian War" The French started conniving to retake the lost territories, including French Canada... (and I'm not too sure they've ever stopped completely trying to retake French Canada). Technically, they stopped when Napoleon was forced to sell Louisiana to the Americans (not that that stopped attempts later to retake it) for much needed cash to pursue its European Wars...
I tend to think that the War for American Independence could have been solved satisfactorily by negotiations between the British and the Colonials, had it not been for French activisim and money.
FOr that matter, French connivance reached such a point that the delegates sent by the US to negotiate a settlement with Britain (conveniently brokered by the peace loving French) were *ordered* to reveal their complete instructions to the French, and to not negotiated with the British without getting the approval of the French, and whatever the French negotiated with the British - even if that meant the dismemberment of the Colonies - they had to agree. Only the fact that some of the delegates went behind the French backs and reached agreement with the British saved the sovereignty of the fledgling nation.
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