Free Supply

[swang30]

Trying to figure out how supply works, and I don't really understand the details.

How does free supply work? It's food to units, right? it's not the upkeep and what not, right? And is it nation based or region based? Is it random which units get the free food? Per turn? forever?
The food that armies use, it's substracted by Forage right? and then it takes the rest of the food from the region? What if that region is in the province? What if part of the army has free supply?

Is preserved foodstore worth building for the free supply? or is it useful only as a hub of operations for a defensive army?

[Pocus]

Free supply are a certain number of supply points provided for free per turn. Units consume supply points, not food.
The conversion ratio of one food into supply points starts at 5, but rulers and some modifiers can improve or worsen that.
Free supply is not free units, there is no change in cost in money, manpower, metal. That's purely region based.
The units who are not supplied are at random, if you have enough supply, there is no need to check which one ... It's determined every turn, as free supply.
Forage is only used if you lack food, otherwise to hit the stockpiles of the civilians and the army.
Province averages food stockpiles, so that's done before supply is used. Once food is balanced, armies eat and use free supply, then forage, then can become unsupplied.

[swang30]

5 SP per food or 5 food per SP?

Wait, so when the unit card and army card says "Food Usage" that's NOT SP? it's just additional Food for maintenance? Is there a difference between a Legion and a skirmisher in terms of Supply usage?
Related, when the army food usage is above region production and forage, the next turn, I see that forage value goes to 0 and it's pillaged. I also might see an out of supply message. All this even though the province has more than adequate food stockpile (possibly not adequate production). Is this different from Supply?

Preserved Foodstore says +20 SP, then that is for the province and not the nation, right? On the other hand, I have a National Trait of 10 "Free unit Support" (I think due to government type?) Is this 10 SP? And how is it applied? to the first 10 units that don't have adequate province supply? Or randomly?

[SuitedQueens]

You don't have to worry about supply mechanic at all. It automatically converted to food required that shows up in the interface. Your units shouldn't forage region if you have enough food supply next turn. Food produced in the region before it consumed by armies, so if you have enough you good. Units also draw food from aligned regions belonging to you, your client state or ally. Its rare to starve unless you are in the open sea or conquered new region which will be affected by huge penalties and proly won't produce enough food.

[swang30]

That's my entire question, it looks like that when attacking, I either have to just keep on going until I can form a province, or strike-pullback-strike if I want to avoid running out of supplies.

It also looks like forward bases for ships are basically impossible.

I built a 32 unit fleet 16 lights at 0.6 "Food usage" 16 other ships at 1.0 "Food Usage". (speaking of which, regular warships don't seem to have a niche. they're strictly worse than heavy worships, have the same speed, and same food upkeep, the other maintenance differences are not significant - some gold, 1 manpower, 1 metal.)
This fleet eats a whopping 26 Food per turn. Putting it anywhere in the front line won't work. New regions and even new provinces don't have enough food production. Preserved Foodstores don't SEEM to do anything, but I'm not sure, which is why I'm asking the question.)

I currently have that fleet parked at a base with multiple preserved foodstore in the province (in addition to the region), I'd expect "food usage" to be lower by some amount, any amount, but it is not. I've got a region in here with >250 turns to grow, so food is being taken away, but I don't know where. There is no -26 in any tooltip. Not on the region level, not on the province level. There's no +20 (or +60) anywhere either. Aegyptus Inferior should be doing well, but it seems to be stalled.

[SuitedQueens]

Here's self-quote from my thread where you can find many obscure advice/optimization techniques:

1) I want to present overseas invasion tactic coupled with creating buffer zone by surrounding yourself with CS states. If you are not in war with enemy faction that you want to invade, you can easily do the next sequence:

If you have been using that Insult Emissary strategy, then at least 5+ nations should be at 50 Relationship level at the very early game sub-turn 20. You can exchange some worthless frontier regions (sometimes 1 is more than enough) and maybe some extra resources if needed to get one or two distant smaller nation regions (e.g. Picts).

Say you play Rome this game. Contact Carthage or Egypt (easy to get to 50 relationship) and trade that distant region that you acquired from the potential smaller CS faction for one or more of coastal regions. Besides, having them close removes penalties from not being neighbors and activates some trading relationship improvements. If you don't want to make Picts or whoever else your CS faction, then you can declare war on them and grab those frontier regions back by force.

The point is that getting coastal regions by exchanging units will leave you the best chances to embark on naval mission without suffering attrition. Otherwise the rule of a thumb is that you need to have exactly as many food ships as transported units.

For more info check these thread that was specifically created to cover that issue without exploiting the game:
Ships food using mechanics - viewtopic.php?f=534&t=105145&p=919195&h ... ip#p919195
More on ships assaulting islands and supplying this type of mission: viewtopic.php?f=534&t=100247&p=867048&h ... ip#p867048
Overseas invasion tactics by great players: viewtopic.php?f=534&t=97715&p=838170#p838170
My Thread: viewtopic.php?f=534&t=105005