How often will that happen? I'm planning on playing as Greece my first time (good ancient/classical units and a bonus with city-states), but I've heard (in several interviews) that city-states will put out "contracts" on rival city-states.
It's going to make it hard to get on good terms with a lot of city-states if you develop a reputation for attacking them. :-(
It's going to make it hard to get on good terms with a lot of city-states if you develop a reputation for attacking them. :-(