Ballista steamroll walls?

[Trajanus]

So I knew the city was going to fall, with my pathetic militia garrison facing an army of over a thousand, but I'd hoped to bleed them pretty well after they had broken through the gates. Sure, they had ladders and siege towers too, but they tend to abandon them once the ram has broken through, and considering they'd brought two of those, it seemed pretty likely it wouldnt take long.

They also brought two ballista units along, but I didn't worry too much about them. After all, my city had some nice stone walls, nothing amazing, but they looked pretty substantial.

Well, the AI decided to hold everything else back while they opened up on the walls with the ballista. I wasn't too concerned at first, but then I saw how much damage they were doing! Clearly, they were going to open a breach. Oh well, I'll just defend that as well as the gate.

Open a breach they did. And a second. And a third. And a fourth. And then just to insult me they knocked out two towers completely as well.

It was over pretty quickly.

Now, I'm no master of siege works, nor an expert in history, but just from looking at the scale of the projectiles these ballista fire compared to the walls , I'm not sure how they could open one breach, let alone four and knock out two towers as well. It seems to me like walls are a little underpowered, in terms of strength against projectiles. Am I wrong here?

The culprits


The devestation

[Revan The Great]

I agree seige weapons are a bit too powerful against walls, but what's the alternative aside from messing with the A.I.? It doesn't matter if the Balista takes down a wall in 3 hits or in 30, the computer will still take it down, the difference is one way you have to sit and watch longer.

[God-Emperor of Mankind]

Walls in cities are weaker then those you find in castles.
Even the full upgraded city wall only take a few hits before it crumbles.
I count maybe 5-6 trebuchet shots for a city wall while it is maybe twice as many for a castle wall.