I'm peaceful player focused only on self-defending wars. I play on Emperor. So far I tried very different strategies to defend my cities and borders from AI and I'd like to share my thoughts and ask you for comments. Mounted units: Very mobile but also very bad at defending cities and borders. The AI always spam a lot of spearmem/pikemen when attacking cities so mounted units are just almost useless... Ranged units: Are good and operate from a distance but do not inflict much damage. Usually I have to shoot 3-4 times to defeat a spearman in one turn not to mention that if I nearly do it can instantly heal next turny and all over again... AI tends to surround city with melee units and then shooting at it with catapults/archers plus attacking with melee... Even if I have walls and oligarchy and garrisoned archer in a city it is not sufficient to defeat AI formation before capturing my city... So even if I get there 3-4 additional archers the time needed to shoot out AI units is too long and AI manages to capture a city. Melee units: That kind of units I found to be the most efficient in city defense and borders defense. These are just extremely good on defending. If I have just a 3 let's say swordsmen agains the whole AI's formation of pikemen/bowmen/catapults it's quite sufficient to ruin AI's city attack. You just have to make your melee units fortify around the city. They get about +50% bonus when fortified and they block a city from AI melee units. Also, when AI while attacking city meet your melee units it seems to concentrate fire on these units first so you have time to damage them with city defenses. Also fortified melee units on your territory heal +20 per turn not to mention they can get a promotion after 2-3 hits and you can get them instantly heal, so they almost restore their full health able to take out another several hits while AI units are much damaged meanwhile. Also you can fortify strong melee unit on top of some resource like iron or lux and that unit really provide good defense preventing AI from pillaging. So generally the +50% fortify bonus + the ability to heal 20hp in your territory + the ability to take instant heal promoton after couple of attacks on your units makes a really good combination for defending purposes and usually means that AI has to sacrifice even 2-3 units and damage additional 2-3 to defeat your only 1 fortified unit. So far I found melee units to be definately the most efficient at defensive wars. In fact I suppose that with a 3-4 fortified melee units around the city you can defeat ANY AI city attack which would be otherwise impossible if you have had 3-4 archers or 3-4 mounted units. The point is not to try attacking AI's units when they enter your territory but just have your units fortified and let the AI attack you. The AI often make kamikaze attacks on fortified units and this way defeating it's own units... Do you have similar thoughts?