[Benjamin]

What it is is that if you have a commander that is doing as written, sneak one turn, attack next, then sneak, then attack again, etc, they are very very hard to catch. The only thing that will catch a sneaking commander is mind hunt, or happening to patrol in the province he is GOING to. I'm a little shaky on that last point, but it's as I understand it.

So teleporting thugs won't catch him, neither will seeking arrows, normal armies have no chance, I don't think remote assassination spells work either. It can be a pain.