From: NE Pennsylvania, USA
Just wanna say here is I did some more testing on this and...
The one thing I left out in my previous post is the formations supply percentage, being a direct multiplier on how much supply the units in it's formation actually get.
Then there is the case of HQ Bias supply.... incresing the actual amount of the supply that units get by 1.5, if adjacent. Must be a cooperating HQ, but I have done some testing and higher level HQs or multiple HQs, have no greater affect. So, guess the only significance of higher HQs right now is providing the extra supply to units where their formation HQ is not adjacent.
Then there is the case of supply units. These can have a major impact. Increase the level of all hexes within the Force Supply Level radius by one level (e.g. Limited Supply, 50%, becomes Normal Supply, 75%) up to the maximum (Full Supply). You will see this in the hexes in the little supply circles. So, this is an increase but also, supply units multiply the supply gained by adjacent cooperative units by 1.5. So, in the case of a unit that would otherwise be at Minimal Supply (25%) an adjacent supply Unit would first increase the supply level in the hex to Limited Supply, 50%, and then multiply the supply gained by the unit by 1.5, giving an overall increase of 3x. So, that is pretty significant, and it is thus wise to use Supply Units effectively, particalarly for units that are not in Full Supply hexes.
Then there is the case of Railroad Repair. Hehe... at first I thought those units with picks and shovels were just worker units with no other function. Wrong! Then can repair rail hexes that are damaged if they start their turn there, and also influnce where autmatoic repair occurs.
Yeah, 'An army marches on it stomach' and in TOAW3, ya gotta get your supply net in order and handle supply effectively if you want to succede in your campaigns.
Hmmm... the OTHER thing... Readiness... this is as important as Supply but pretty much goes up and down by itself. The only thing I have found that increases Readiness recovery is not moving (even if you attack) a unit, which increases Readiness recovery by around 50%.