I have recently played a nice little game called Advanced Strategic Command, and while the graphics sucks, the combat strategies rule! It is based on the old dos games Battle Isle, and instead of putting units into defend mode there is an option called Reaction Fire. It works basically this way:
If an enemy unit enters a field close to the Reaction Fire enabled unit, it will be attacked by that unit without the RF unit suffering any damage.
The RF unit will be immobile for the next turns untill reaction fire is disabled.
It could actually be used by largely any unit. For melee it could be called ambush, and archers it could be the volley shot. Though it does seem to fit gunpowder and tanks better and artillery the best. You walk within the range of an artillery possition, good chances are they will try to take you out, while in Civ4 (and rom) you can nice and easely move 30 times around artillery without consequences (if you have enough moves that is).
Just my 50 cents
If an enemy unit enters a field close to the Reaction Fire enabled unit, it will be attacked by that unit without the RF unit suffering any damage.
The RF unit will be immobile for the next turns untill reaction fire is disabled.
It could actually be used by largely any unit. For melee it could be called ambush, and archers it could be the volley shot. Though it does seem to fit gunpowder and tanks better and artillery the best. You walk within the range of an artillery possition, good chances are they will try to take you out, while in Civ4 (and rom) you can nice and easely move 30 times around artillery without consequences (if you have enough moves that is).
Just my 50 cents