How do city attack strength mechanics work?

[Zaldron]

This may work exactly the same in vanilla, but I haven't had my cities directly attacked by concerted armies in vanilla in a very long time, so I'll ask here:

Would it be expected that 3 skirmishers (15 str) and a cannon (~20 str) would take my 35 str capital from full health down to about 15% in one turn? I would expect that a 15 str skirmisher vs 35 str would inflict 1-2 damage and take ~15, but they probably only took 4-6 damage from the attack and did a huge amount of damage to my city.

Is there a special bonus vs cities? Does the AI get a bonus vs cities?

EDIT: This was Japan effectively winning conquest (I had to quit having only one other newly founded city - I was pursuing a cultural victory) on turn 199 or so, long after I've ever seen an AI be militarily competent vs humans.

 

[wobuffet]

Last game, one super-promoted Cannon pounded my City (15 pop or so, no defensive buildings) for 18hp in one turn. I don't know if that was because of a bug or not, but if it happens again I'll report it. (This was v146.4 or so.)

Note (mostly to self): Cities have 40HP as opposed to Units' 20.

 

[pthmix]

I think the AI gets a anti city bonus on higher difficulties (+50 percent on emperor if I remember correctly). AI units should have a promotion with a silver triangle. You can see the promotion if you mouse over them. It is not visible above the unit icon.

 

[lordrune]

The AI's pretty good at getting enough numbers to take your cities, so if you can't challenge them in the field, you're always going to have a problem. Siege weapons are potent especially if they've been upgraded a bit.

 

[Thalassicus]

I haven't had my cities directly attacked by concerted armies in vanilla in a very long time

AIs have a city siege bonus in vem for the reason above, and also to help militaristic leaders succeed in AI-AI wars.

 

[Zaldron]

AIs have a city siege bonus in vem for the reason above, and also to help militaristic leaders succeed in AI-AI wars.

I can understand the motivation, it's just pretty disconcerting when three 15 str melee guys waste your 35 str city taking minimal damage.

I was maintaining a minimal (~4 unit) army to attempt to defend, but the AI super-knights (9+ promotions) would destroy pretty much any melee unit I deployed in an attempt to defend my city, so I pulled back to try to let the city take some of the melee attacks. That didn't work out too well obviously.

 

[Bernd-das-Brot]

Is there a special bonus vs cities?

From my experience there must be some bonus against cities (or their HP are counted in a strange way). The AI-bonus is new (I love it!), but even in vanilla attacks against cities had strength outcomes in favor for the attacking unit. Unpromoted Swordman (12) or horses attacking walled cities (18) and estimated losses were ~3:8 regularly.