When a province is under siege, you should be able to buy another 1k garrison strength at the cost of population (limited to larger cities of course) Possibly repair breaches that way as well. No reason at ALL Constantinople should fall to 2000 infantry with it's 200k population, only 1% of which is defending :wacko:
Barring this it'd be nice to experiment with city_population increasing local defensiveness. You're right that a big city should be harder to seige...
This was the case in the real world at that time, and it still is a problem today
No it wasn't. Not to this extent. Atleast not in this era. You might've had a point during the middle ages when there was still crusades.
Castille will dow and take provinces in the middle east before trying to absorb Navarra. The ottoman Empire will prefer invading Italy over Egypt. China will prefer to expand into siberia rather than subdue korea or south east asia. Etc, etc. That's just wierd.
Obviously a religious enemy should carry some weight. But given the choice the AI will fight a religious enemy a lot more than it's actual rivals that hold land that might actually be valuable to them.
This isn't due to religious CB's either as I tried removing them and this had no visible effect at all on who the nations chose to fight when given plenty of both kind of targets.
Also outside of europe it makes even less sense. In my indian example muslims and hindus frequently allied against common enemies in real life and there was never such a thing as a religious coalition during the entire timeframe of the game.
It'd actually make more sense to have members of the same religious groups war more than against heathens. Shiites and Sunnis fought many bitter wars after 1501 as did lutherans, calvinists and catholics, and so on.