What would be the immediate ramifications if England, seeking to weaken France and secure Aquitaine, convinced Raymond VI, Count of Toulouse to continue to refuse to help the Papacy and French Crusaders against the Cathars, and also gave money and troops to the Cathars opposing the Pope?
Could this cause the Cathar/AlbigensianCrusade to fail? Obviously, in OTL, the immense manpower and resources of the French Crown made it impossible for the Cathars, and indeed, southern France, to succeed.
But southern France is quite rich, so with the help of the English, could they perhaps succeed in holding off the northern French soldiers?
And what if the Crown of Aragon decides to interfere, sending aid to the beleaguered Occitan Counts in Toulouse and the surrounding areas?