Just curious as to whether this is working as designed.
In a PBEM campaign game as Prussia, the East Prussian Army had, as expected, been defeated by the 160,000 Russians. Both armies ended up in Koenigsberg. However next turn, when I tried to move the Prussians out of Koenigsberg, setting them with army orders to retreat if engaged, they instead remained mired in Koenigsberg where there were four further battles they all lost with a total morale loss of about thirteen. To compound matters, it ended with the Prussians, instead of retreating southwest along the road towards the rest of Prussia, retreating east - towards Russia mind you - into a trackless forest.
I have seen this happen as well in several AGEOD American Civil War PBEM. An army will be defeated but simply not be allowed to retreat the next turn, remaining "stuck" for a ruinous series of unavoidable additional encounters. Then they retreat in a seemingly random direction. I have been on both sides of this - my Confederate opponent lost an entire 50,000 man army this way when the CSA army, instead of retreating towards its depot, retreated out of supply into the mountains.
I hope the retreat and battle routines can be looked at some more. I realize that at times armies were routed. But they were even then usually able to retreat - and retreat in a direction they chose.
Being stuck in an additional battle and being unable to retreat and then retreating in a random direction happens too often for these eras.