We don't mess with your warfare. We didn't yesterday, we haven't in the past.
Don't mess with ours.
If you do, our city relations will suffer needlessly.
Now you have the esteemed position of Field Marshall in your city, I would hope you see the ability to restrain yourself from needless interference in fights that do not concern you, are already balanced, between two cities you hold good relations with, as an important part of the representative aspect of your role.
If you don't see that, I can only hope your Prince reconsiders your appointment.
Written by my hand on the 26th of Eleuthral, in the year 1154.