Zeeter, the glory of AI is that you don't have to deal with micromanagement. I intellectually appreciate what you are saying about supply vehicles. In both ancient and modern times caravans/trains are used. Such things could be interesting, but I tend to think - tedious. The less nit-picking work the better playability. What I would like to see is no visual component to supply nor the necessity of manually maintaining supply, except for the use of a beach or bridge-head (taking the place of the normal City determinant) as they are called for units operating overseas on foreign soil, and otherwise, outside the AI system's acknowledgment of the need to use aircraft to bring supply to forces outside of supply chains.
Its so simple. Unsupplied units attack and defend at half strength. On the battlefield, being attacked simultaneously at 180 degrees of separation would likewise incur the effect of being out of supply, and unless your defending unit had the inferred Promotion of 'HEDGEHOG', which would counter being surrounded and cut-off (NOTE: PIKEMEN are natural Hedgehogers. That is the style of combat the Pike was designed for - both front-line and circular phallanx type formations), they'd be at half-strength, and if there was a retreat for surrounded defending units they'd be significantly disabled, and if not destroyed.
Its so simple. Unsupplied units attack and defend at half strength. On the battlefield, being attacked simultaneously at 180 degrees of separation would likewise incur the effect of being out of supply, and unless your defending unit had the inferred Promotion of 'HEDGEHOG', which would counter being surrounded and cut-off (NOTE: PIKEMEN are natural Hedgehogers. That is the style of combat the Pike was designed for - both front-line and circular phallanx type formations), they'd be at half-strength, and if there was a retreat for surrounded defending units they'd be significantly disabled, and if not destroyed.