Originally Posted by
Shigawire 
Here's an idea I had back in 2006 for a mod called EB - but we were unable to because of hardcoded limitations.
Full yet simple system for army supply, attrition, morale
Premise: Army/Legion must be identifiable with its own "traits" - Perhaps this is what CA is trying to do for Rome 2?
In any case, the idea was this: The Army/Legion have their own respective traits, morale, supplies.
Supply:
Newly formed legion starts with 100% supplies, in home territory.
Maximum 90% supplied in colonies (if you play Rome, it could be anywhere outside Latium province)
Crossing into neutral or enemy territory, the "countdown" starts. The supplies at 100% drop by X% each turn, until it's near starvation point. This countdown represents the distance and perseverence of the supply line. For example local civilian guerilla attacks can reduce the supply line.
The rate of the countdown (X%) will require hands-on balancing, and is wholly dependent on how many turns a year, move distance per turn etc.
Historically, each "commeatus" (supply line) consisted of depots, granaries and a port. Each commeatus had enough food to last for at least 1 campaigning season. So 2 of these supply complexes (commeatus) would give you the ability to field 1 army for 2 campaign seasons - or conversely 2 armies for 1 campaign season.
Field 2 legions from March -> Winter,
or
Field 1 legion from March->winter->March->winter (2 campaigning seasons)
Attrition Zones
Move your army on terrain like this, start to lose both morale, supplies and/or lives (to varying degrees)
Winter in enemy territory
Mountain pass (Alps f.ex.)
Deserts
Marshes
Foraging on specific tiles on coordinates of strategic interest:
Move your army over any of these, and get a temporary reprieve from poor supplies/morale
Foraging will lower your relationship with the host country. So if you are foraging in Neutral country, you could end up alienating them.
Grain fields, estates, olive trees, farms (reset supplies to 80%
Or perhaps a granary (f.ex. Cannae) (reset supplies to 100%)
Oasis (handy if you're in the Desert) (reset supplies to 60%)
etc
- Tech upgrades -
"Greek siege tactics" P. Sulpicius Galba was impressed when he first witnessed Macedon's siege train. 20 years later in 190 BC, the Romans had copied the Macedon siege model, and for the first time started constructing their own siege towers and machinery for the assaults.
-Reduce supply usage by 10%
-Allow construction of siege towers before assault
-Sapping
-etc
(can be broken down into separate techs)
Operational Supply base
-Moving forward the supply line's anchor. This can be as little as a day's march from the Army.
Increases supply line range. Return your army here to become 70% supplied
You are till vulnerable. if the enemy hits this, your army will suffer a great morale drop.
Maintaining this should cost money per turn. Extending a campaign into deep territory should be expensive.
Legion/Army retinue and traits:
Hunters
Hunting becomes less of a chore, more of a sport. More meat for the dogs of war.
Criteria: Forage successfully in forests or near hunting lodges without enemy interruptions 3 consecutive times.
Award: +5% supply per successful forage attempt
Hunter 2 (replaces Hunter 1)
Criteria: 6 consecutive times
Award: +10% from foraging
etc++
Cunning Quartermaster
This man cleverly reinvests your officers' superfluous rations to the common soldiers without either party knowing.
Criteria: Maintain a supply of over 50% for an entire Campaign Season
Award: 5% less drop in supplies per turn
Army Morale
When Morale is 100%, the soldiers (as normal) don't break as easily in combat.
If the leader is exceptional, the Army Morale can be maintained at near 90-100% into the deepest campaigns (Alexander, Hannibal).
Morale will drop if you lose battles, or if you lost an Operational Supply Base, or other major negative events.
If Morale drops, you can return to friendly territory and spend money on army entertainment f.ex.
Supply + Morale interaction
When Morale reaches 0%, wholesale desertions ensue.
If supplied over 50%, Morale gets an automatic 25% minimum position. Morale will not drop below half of your supplies. The men may be sad they lost the battle, but they still have enough supplies to get them through the day, or maybe back home.
Morale is always affected by your supplies. If you lost a couple battles, but are still well supplied, your army will not desert so readily. But your Supplies are affected by your wins/losses as well. Winning over the enemy and capturing their own supplies, can make your supplies go up. So if you lost a battle, the chances are you lost some supplies in the process.
A brilliant leader can still make his men follow him, boosting morale by actions he take. Some actions cost money, etc.
So you have 2 levers to affect and alleviate your chances of losing your army completely.