From 85 to 89, I served in a support battalion of the 2nd Brigade, 9th Infantry. My company was mechanical support, meaning if it broke, we fixed it. Another company transported supplies to the forward combat troops and a third company supplied medical support.
All told about 600 people in our battalion.
7mm
I think you may find this interesting, referencing what it took to keep an army in the field. All of this was accomplished with the relatively rudimentary forms of record-keeping and communication available.
https://transportation.army.mil/History/PDF/Peninsula%20Campaign/Rodney%20Lackey%20Article_1.pdf
