It, Doesn't seem to be that complicated. Let's not make it sound all that complex. Upgrade the army in the city which contains the Army build building. Such as the Military Academy, which has those flagged by default. Sadly , if I remember right, that will satisfy the technical double talk. We're not talking about generic armies.
You do need to have a Barracks (i.e. Veteran Ground Units) or it won't upgrade, not just the Military Academy, which doesn't have that flag - which, was my point, and completely relevant. The other point I made was for those who don't want to have obsolete units in a more modern army.
Let your posts be relevant, and avoid redundancies. If you're out to impress anyone, do it somewhere else.
Well, that was pretty rude - don't know where that came from - sorry to have bothered you. And, I was only trying to help anyone who was thinking about upgrading armies - it wasn't for your benefit. And, really, I don't need to impress anyone, particularly someone who has such a negative history on here.