[Velusion]

Meglo - I'm not sure if you are aware - but using stealth commanders to sneak non-stealth troops out of a besieged castle is a bug.

From Edi's List: BHV Non-stealthy Units Sneaking Out of Besieged Castles Non-stealthy units can sneak out of besieged castles. Requires stealthy commander. Give commander move orders out of castle and he will sneak. Add non-stealthy units and move orders change from sneak to move, but orders are executed on hosting anyway. Can be used to evacuate sieged castles to friendly nighboring provinces and/or attack neighboring hostile provinces. This seems to be a special case of the above issue.

Perhaps I'm wrong, but it looks like this is what you did to escape the seige of your capital.