Thanks for the responses.
I definitely understand much more than I let on about the underlying mechanics at play that led to the result, but the play experience was unusually immersive only to be dumped on by a missing system.
I simply felt it was best to most accurately describe my experience, to emphasize that this ought to eventually be implemented in a way that works in favor of these emergent stories.
Of course I lost face when the city I was entrusted with fell, but I wasn't going to win that seige.
In the end Derthert lost nothing, the city was under Vlandian control again in a matter if days, and I was specific about enumerating the number of high-profile prisoners that I had accrued, each of which ought to relieve pressure on one front of Derthert's war.
Time since the loss of the city, solo responsibility retake, mass POW acquisition, these are all things that ought to be added into account.
I simply felt I had experienced something that put that on display in the specifics rather well.
Cheers!