Although the readme says you can, units loaded into an Army is not unloadable in civ3. (bug?? ) I find that in the Editor the Army unit "unload" checkbox is not checked. Perhaps if it is checked, units can be unloaded from Army!! Has anyone try this before? I'm having a new and good game so I can't test it right now.
It should work. You can also select the *Blitz* ability, which gives it the ability to attack 1/move. You'd think armies would be at LEAST as effective as solo units.