The battle pace should be slow enough to have some time to understand what's happening, see what can be done and order it.
0 A.D. - The vision seems to go toward well prepared battles, not that much micro (without rejecting it).
A lot of battles were also won with the use of fine tactics like placing soldiers in an original and unexpected way (ref necessary), ambushing or striking from front and back (ref necessary) or make an unspected move during the battle (see battle of Gaugamela)
But it has to be fast enough not to be boring, add a little stress and get advantage of the suprise effect.
There is a balance to find between long battles that allows smart manoeuvres to reverse the situation and fast enough to allow raiding.
If battles are too long: units will stand a long period of time and movement must be set slow not to be able to rebuild units from the time and/or send reinforcements from far away. This also means if you want to send a raiding party upon a weak point, this party must be very large to have a real impact before reinforcements are set or targets retreating to a strong point.
If battles are too short: units will die very quickly and the outcome will be known before the battle is engaged by just evaluating the forces. There won't be time to put some orders and most units would even act better striking once or twice before dying instead of trying to do something smart with them.
The aim is be able to pick units or groups of units and do something more that rush in the pack. Like using the speed of cavalry to go around the main infantry line to pick the support line from the back and then outnumber this front line (or cut retreat). This could also be hit'n running, splitting troops to open a gap...
But this should not give enough time for an unprepared army to set in order and fight back effectively (balance between fast skirmish and ordered battle).
For a raid to be feasible without having to mass units, a 5 ranged to 1 would result almost in an instant kill. Because it's a lot harder to be 5 on 1 in melee, 3 should sufficient.
That means the overall Damage/HP should be around 5 or 6 hits to kill or between 1 and 2 seconds to kill for this party. This greatly varies with rate of fire, speed (melee/range) and effectiveness against the target.
Considering the global rate of fire of units to be around 1 hit per second, this also means an equal engaged battle between two small forces with everyone engaging fast would length for around 5 to 7 seconds.
Finally, this also means that with multiple rows (not all units fighting at the same time), a large battle would length from 20 to 60 seconds.
These are some stats that tries to reflect that.
- Movement speed around 7 (infantry) and 12-14 (cavalry)
- Range between 35 an 60 to leave some space between melee and ranged units and use it wisely.
- HP 60 (infantry), 100 (cavalry), 250 (elephants)
- DPS around 15 or 20, varying with range, speed and other to give some strengths in some situations
- Armour varying between 10% (1 armor) and 50% to set strengths and weaknesses
These figures are presented as a reference and can be evaluated only through multiplayer games while keeping an eye on the whole (like map size, vision, resource spreading...).