They really can't defend themselves for some reason. They don't upgrade their units. They parade their weakness in the streets with their warriors in the Industrial Era. They don't build military units matching the era. They don't fortify their troops to withstand attacks and instead blindly lash out like what barbarians do. It's almost like City States were made for the AI to conquer because AI's level of aggression against them is off the charts. They conquer them as and and when they like, whenever they like, and the city states just let them. Remember a time when allying with many city states usually denotes a peaceful. diplomatic game? Now the more allied City States you have, the more you have to go to war to protect them because AI's just looking for every chance to devour them. How did the developers manage to turn a significant element that represents peace and diplomacy into an excuse for war? Talk about the futility of diplomacy in Civ 6. You can't ask the AI to stop, you can't bribe them into stopping like in Civ 5, you can't even declare a protectorate war if the aggressor is a declared friend/ally. The AI simply does not consider the fact that it is invading your City State, in fact it would appear that they're doing it on purpose. How stupid is it that a player should avoid making friends if they want to keep their city states? How stupid is it that given the amount of investment required to protect city states, the player is better off using that force to conquer the AI? At one point I thought to do an experiment on Emperor and see how bad City States were at defending themselves. Earlier on England(Declared Friend) had attempted to conquer Toronto, of which I was Suzerain of and I promptly levied the city state's troops and surrounded the city state. England couldn't get past those Meat Shields for 30 turns. Near the end of the levy I upgraded them all to the Information Era(Mechanized Infantry, Helicopters.) Guess how well they fared against Redcoats and Field Cannons later on? They lost all the advanced troops after a brief struggle and I had to step in with a protectorate war. Mechanized Infantry and Helicopters lost against Redcoats and Field Cannons. How? Reckless attacking without fortifying and healing that's how. They simply don't heal their troops in war, like Barbarians. I'm sick and tired of having to surround my beloved City States with meat shields to protect them from "friends". I guess I'm more sick of how everything is so war centric in Civ 6. I've attached a couple of screenshots below for a different "friend" in the same game who loved attacking my city states. She was at it since the Medieval Era and my vanguard were initially horsemen.