Is it possible to control backup armies?

[Sorkenlol]

When you attack a city or an enemy army with 2 armies, you get to choose one of them, if I choose one, I can't control the other. Is it somehow possible to control both?

[Celsius]

Yes, you can control both.

[Jagdpanzer]

When you attack a city or an enemy army with 2 armies, you get to choose one of them, if I choose one, I can't control the other. Is it somehow possible to control both?

You can control the 2nd army by deselecting the AI-controlled option of the 2nd army in the pre-battle scroll (the screen that you get before the battle where you can choose to fight, auto-resolve or flee).

, the red knight

[Monsieur Alphonse]

When you attack a city or an enemy army with 2 armies, you get to choose one of them, if I choose one, I can't control the other. Is it somehow possible to control both?

Like Red Knight described but only if both armies have less then 20 units together. You can't control more then 20 units. In Kingdoms there is an option to control other stacks then your own, but you only can control them as a hole army but not individual units.