Damaged stockade mystery

Playing as the Julii, in 215 BC I besieged a Gallic town, Burdigala (SPQR Mod-Bordeaux?), built a ram and attacked next turn. I noticed on the map a Gallic warband on the far left perimeter of the town. They seemed to be guarding a piece of stockade that, although not completely destroyed, was looking distinctly worse for wear, roughly 60% damaged I'd guess. They didn't even notice my urban cohort bearing down on them until it was too late, as if they were expecting something or someone to come through the damaged wall.
After taking Burdigala I took the settlement tour to get a better look. The damage was still evident although the gates I'd smashed in didn't have a scratch on them. AFAIK Gaul had only ever been at war with the Romans, ie me, and this had been my first visit to Burdigala.
What caused the damage? Was it aliens, one hell of a party the night before or just slovenly practice on the part of the Burdigala Town Council Maintenance Department? The only thing I can think it could possibly be is rebels/brigands but do they use siege weapons?

Rebellions randomly damage buildings and that is more likely the cause. As far as the A.I. guarding damaged walls ......... That's just a bad feature. Just a little info rams can't ram damaged walls that have damage from a previous engagement and that is a bug.

I think you're on the right track. I think it's pretty obvious that prior to your besieging that town the Gauls threw an all night wine tasting party that got a little out of hand. You know how naughty those Gauls can get when with a little fermented extract in their veins. The demise of poor Hasdrubal is proof enough that you should never let a Gaul drink on a school night! ~D

True story.

The night before the battle of Waterloo the barn doors of La Haye Sainte (a key defensive position in the centree of the Allied line) were removed by allied troops who chopped them up for firewood.

Thus for the entire of the battle the next day german garrison were forced to try and defend a 6' wide gap in their defensive perimiter. Fortunately, it was on the western side of the farm farthest from the road and so only got limited attention during the opening assault by D'Erlon's Infantry but it was this door which eventually gave the French access later in the day when the farm finally fell.

i had this in my settlement twice i was playing the gauls and wasbesieged by brutii and julii forces i wa was placing my forces when i noticed the army was split up so i went to look and there was a huge gap in my stone wall
and before the siege i checked and my wall was totally good no damage nothing. it happened another time with a wooden wal also a total mistery
i dont no what it is but it is anoying

Even stranger - I took a town with a wooden wall, making a big hole in it in the process. My first thought was to build stone walls, so I didn't bother repairing the old wooden wall. Imagine my surprise when a few years later someone came to besiege that town - and I discovered that the new stone wall had a hole in it in exactly the same place as the wooden one had.

It didn't matter - it worked in my favour as the Parthians (I think) just kept sending wave after wave of cavalry attacks at the breach, guarded by five or six units of phalanx troops. Repelled the siege and caused far more casualties to the enemy than if they'd just assaulted the walls as normal.

maybe that happened to me with the stone wall to in dont really know