My armies won’t upgrade once built and loaded.
I asked about this in another thread a while back, and the answer I got was that Armies
can upgrade, but apparently only in a town which has both a Barracks AND a Sm.Wonder with the 'Build Army' flag (e.g. the Mil.Acad. in the epic game).
I don’t like the idea of being stuck with an army group of obsolete units.
Neither do I, but you can always disband obsolete Armies (for 100s, in the epic game) -- or fortify them in your capital for ceremonial purposes!
Alternatively, if you give Armies the 'Unload' flag, then you should be able to evict the component units -- but you then can't put your Armies onto boats (although you might still be able to Airlift them... Hmm...)
Unless anyone can tell me there’s an alternative I’m going to try this plan.
*snip*
The upgrade from Pre-Army to Army would still require a Rax at minimum, which the AI wouldn't necessarily understand. And even if it did, the AI might not use it anyway -- it tends to use its MGLs to rush projects, when it acquires them in a town.
(And when it acquires them in the field, I assume it will only bring them to a town if the MGL appeared within its own territory: in a recent game, I saw it leave an MGL out in the open, 1 tile beyond its own borders, turn after turn, until I finished killing the stack it was hiding under).
You would still lose the units inside the army but you can reuse the army.
Not sure what you mean here. The 'Pre-Army' presumably wouldn't load any units, and an Army which upgrades directly to more modern Army, would keep any units it was already loaded with through the upgrade.
To be able to recover/ recycle the individual units that an Army was loaded with, you would also need an intermediate upgrade-step between Armies (maybe call it a 'Great General', and re-use the MGL-graphics?), which has zero transport capacity: I
believe that the intermediate would also need the King-flag (to make it unbuildable but still accessible). Upgrading to the intermediary would automatically unload the units, which could then themselves be upgraded, and reloaded into the upgraded Army. The AI almost certainly wouldn't realise this, though...