Resarch nukes
Try and attack differant city if possible, or get your redcoats with high promotion that gives 1st strike chances (forgot teh name). This promotion also gives you resistance to collateral damage.
Next thing is to attack that city with lots of spearmans/pikemans as the game AI will make em fight cannons instead for black knights.
Also try and pillage his resources, so he will not be able to make neighther black knight nor cannor nor musketer. In order to secure such advantage, set up 5 or more unit defance on resource with pillaged improvement. You will need 2 medics, 2 units with resistance to collateral damage and "main" defending units with eighther high defance promotion or guerilla (hill defance bonus) depending where the resource is placed.
Another thing is to dont make big stacks, couse they get collateralled. "sorround the city" on its every title, this will make city population drop fast + he will have a hard time in production. Also know that Paris is French only city with production, Lyon is only grassland, Orleans (the one under Paris) has only 1 or 2 hills.
Or if you dont want to take Paris eighther sign peace, or start economical war. Change civics to the ones that will allow you to sustain in war for long. Feudalism, Police State, Despoteis (Heridary Rule if you have big war weariness), Theocracy, Caste System or Slavery(to train and hurry unit production in enemy cities you have conquered allready).
Sorround citya nd make it starve to 1 population, bombard defafances is pointless when you have gunpowder units, pillage improvements and roads.
Edit: ow and yeah - resarch nukes.
