Supply

An army has to be fed, fuelled and resupplied, and not every province can do that for every army. Supply in Atomic Dawn works on two levels: each province has a supply limit on how many brigades it can sustain, and each brigade is either in supply, connected to its homeland, or cut off.

Supply limit

Every land province has a supply limit measured in full-strength brigade slots. It comes from the province's population and its Infrastructure:

• A province with no railroads or roads can sustain soldiers equal to 25% of its population.
• One with full infrastructure can sustain 50%.
• Values in between are interpolated, and the total is divided by a standard 5,000-soldier brigade and rounded down.
• Every province can always sustain at least one brigade.

A densely populated, well-connected industrial province can therefore hold a large army, while a remote mountain valley or desert oasis may support only a single brigade. Infrastructure starts from the railroads and roads on the map and changes as countries build them up and wars wreck them.

Devastation lowers the limit, by up to half in a fully devastated province, so a long fight over the same ground makes it harder and harder to keep large forces there. National and provincial Supply Limit modifiers adjust the result.

While the brigade view is open, hovering a province shows its current brigade count and its effective supply limit.

Attrition

Countries strongly prefer to station brigades below the limit, but frontline operations can push past it for a while. When a province holds more brigades than its limit, every brigade there loses 5% of its current strength each month. National and provincial Attrition modifiers change how heavy that loss is. Supply attrition also wears down brigades' morale.

Concentrating a decisive mass of troops for an offensive therefore has a cost: the longer they wait crowded together, the more of them are lost before the attack begins.

Separately, countries fighting with a guerrilla doctrine inflict attrition on enemy forces operating in their territory, independent of supply limits.

Staying in supply

A brigade reinforces its losses and recovers morale only while it is in supply:

• on its own country's soil; or
• on friendly-held land that connects to its homeland over land; or
• on friendly-held coasts reached through seas the enemy does not deny.

An army that breaks through and is then cut off behind enemy lines cannot rebuild itself. An expeditionary force overseas is supplied by sea and cut off when the enemy takes control of that sea (see Air and Naval Warfare). Enemy air interdiction over a brigade's region can also stop its reinforcement.

Where a brigade is in supply, the pace of reinforcement still depends on the infrastructure where it stands: with no railroads or roads, replacements arrive at half the normal pace. Reinforcements come from the national Manpower pool and arms stockpile, so a country that has run out of either cannot refill its brigades however good their supply lines.