[Chazar]

Ahh, not sure if this bug is already known:

A stealthy commander can lead non-stealthy units out of a besieged castle: Remove all non-stealthy troops from the stealth-commanders command. Set him/her to move (not sneaking, ie. with ctrl-click) him to another province. Reassign the troops to him. The move command remains and is executed with all non-stealthy troops following their commander out of the besieged castle without a fight.

Tested with a Seraphine and a dozen of blizzard warriors. They are all flying, but since non-stealthy flyers cannot leave a besieged castle (why after all?) the aformentioned behaviour seems buggy to me...although from my point of view its a nice feature!