Use a frigate or ship of the line to bombard a coastal city's defenses to 0% then attack with cannon directly from your caravel, merchantman, or galleon and you will kill every defender and be able to raze their city with no risk. Just rest cannon to full health between attacks, you will be able to rest one cannon faster than the enemy can bring reinforcements. And if they try to bring in reinforcements by sea you can sink their ship first. At best a defending cannon has innate 50% defense, 25% from hill, and 50% from rebel sentiment if its at 100% sentiment in the city, that equals 6.75 str. At best a defending infantry has 25% fortify, 25% from hill, and 50% from rebel sentiment, that equals 6 str. At best a defending dragoon has... well nothing, because dragoons get no defensive bonuses so hill wont matter, rebel sentiment increases defensive bonus so that wont help dragoons, and the dragoons innate 50% vs cannon reads as when "attacking cannon", so i dont think that applies either. That leaves just 4 str for dragoons that defend. Now an attacking cannon has innate 100% bonus attacking cities, and negative 20% when attacking from sea, so thats a base of 5.4 str. Kill one unit and get bomb 1 then you are 6 str next attack, kill another and get bomb 2 and you are 6.75 str on the third attack. For the defenders to have a chance they need soldiers or cannon in the city that is built on a hill and they need to maintain 100% rebel sentiment. The only defense against this tactic is to buy or build a navy of your own. And you need at least 3 privateers, 2 frigates, or a ship of the line to stand a chance at fighting them off. I just tested this out with a ship of the line a caravel and 2 cannon: one of my cannon died in the first attack, the other one killed a defender and started to earn promotions of bomb 1 and 2. You could attack indians first with a dragoon defending your two cannon and earn bomb 2 on both cannon by the time you destroy one native village, then you would be unstoppable on your naval attack. They need to make 2 changes to fix this loophole in the game mechanic. First, change it to 50% negative when attacking from sea and 25% negative attacking across a river. Second, make a build command in your cities that allows you to make limited repairs on defenses say 30 production is 30% defense repaired but every turn you repair 10% less a turn for that same production. Normally i play spain and build a quick army of dragoons and cannon to rampage around with... on land. But if you are min maxing your best bet is a galleon of cannon with a warship or two defending it as you raze every coastal city.