There's a specific fort type in the game that becomes darn near impossible to take if it's filled by Laotian fire arrows. It's the one where there's a massive dip between you and the actual fort, and then you can just walk right into the courtyard, where you're assailed from all sides by enemy archers.

Walking in gets you killed.
Shooting the guards near the entrance and going in gets you killed.
Killing literally everything you can reach by attacking from the ledge overlooking the fort in the back, then walking in still gets you killed. There is no way to make it work. Going in will always result in your death.

I dare any of you to try it.