I have had a vet army, but I cannot tell you how it came about, but here is the low down on armies for C3C:
Attack bonus with:
Neither Pentagon nor Military Academy: (6+6+6)/6 = +3
Pentagon only: (6+6+6+6)/6 = +4
Military Academy only: (6+6+6)/4 = +4 (rounded down)
Both Pentagon and Military Academy: (6+6+6+6)/4 = +6
With Pentagon and Military Academy, assuming you load 4 units of the same type into each army, the net result is to simply double their attack and defense stats, because the bonus is (4*X)/4 = +X Which makes a 4-Cavalry army into a 12/6/4 unit.
Movement is +1 to the slowest unit in the army.
Armies have a built in radar function and can see two squares.
Free pillaging.
Units specail ability is lost if not homongenious.
Armies are treated as if you had battlefield medicine for healing. They fully heal in a city with a barracks, just like a individual unit.
Att/def is calculated for the currently attacking or defending unit, so if it is a mix army, they change to reflect the one fighting at that time.