
Those are then combined to outfit a unit while it is formed and put through basic training. Instead of ordering whole complete units, the player now has industrial production to manage, with abstract "factories" building different types of hardware. Changed also was the unit production system.
IV came out with another new system that doesn't require micromanagement of sending equipment to units as that is done automatically, but has an abstracted infrastructure & unit supply system and after the Man the Guns expansion, fuel for vehicles, planes, and naval units. People either praised and wanted more of the details put into it or consider it too boring. It introduced fuel and required crude oil to be refined to make it, the transport capacity of infrastructure, detours, use of supplies and fuel for the transport of supplies and fuel themselves and bottlenecks.
III attempted to make logistics more realistic.
II used a simplistic and abstract system that kept track of a "Transport Capacity", a counter equal to twice the IC size plus tech modifiers and difference between stored and used supplies and oil. Changes in logistic system between games are by far the most contested part each time new game shows up or is patched up. It's nowhere near as volatile as discussions about logistics, but the research system is probably the most memorable thing from the original game and is still discussed to this day. Of course, each following system from sequels has its own supporters and they generally don't get along well. To this very day there are people who consider the research system from the first game note Each technology requiring industrial capacity invested into it, thus being based on nothing but wealth of the nation measured in the size of its industry, meaning the more you conquered, the more simultaneous research you could afford to be the best in the series, as it didn't have any sort of arbitrary mechanics (tech teams, leadership or research slot number) attached and further motivated people to conquest.