...sorry but, nope ...counterattacks will only help the AI if you take the capital of a any faction...this is to make it nearly impossible that Players blitz early. If you want to take a capital you have to bring 3-5 Legions to succeed and to hold it...this will help that Players must concentrate their forces for successful campaigns and will be short in other theatres thus having no offensive power in more than one spot at a time....
If the Player looses a city he has to reatake it by his own means...
"The ones who run today will live to fight another day"