A division without supply loses organization, speed, and combat power even with the best equipment in the game. Logistics is the mechanic that decides whether that equipment actually reaches the front or sits stuck somewhere on the rail network.
Why It Matters
Supply isn't just ammunition — it covers equipment, fuel, and everything a division needs to operate at full strength. Below a certain threshold, penalties to organization and speed kick in, and if it's cut off entirely, the division starts losing equipment without the enemy firing a shot.
The Supply Network
Supply travels from your capital and production centers to the front along railways. The better a province's rail level, the more supply can flow through it without bottlenecks. In territory with poor infrastructure — Siberia, inland China, much of Africa — upgrading the railway isn't enough on its own: engineers can build supply hubs that extend the network's reach beyond the last usable rail line.
Trucks and Logistics Company
Where the railway doesn't reach, the game automatically assigns trucks to cover the gap, at the cost of steel and manpower. The motorized or mechanized logistics company, as a support unit in the division template, cuts that division's supply consumption and widens its margin before penalties start — worth it for divisions that will operate far from the rails, like the spearhead of an offensive.
When You're About to Run Out of Supply
Supply problems almost always show up at the same three moments: an offensive advancing faster than your rail network can keep up, an amphibious landing far from the nearest supply hub, or a pocket the enemy has deliberately cut off. If you're about to attempt any of the three, build supply hubs ahead of time or plan for your spearhead divisions to arrive weaker than you'd expect.