Supply and Logistics

Supply and ammunition are not the same resource.

Two separate resources

ResourceWhat it does
SupplyKeeps an army operational on campaign. When it runs out, morale collapses.
AmmunitionLets particular units make particular attacks. When it runs out, that unit falls silent.

Supply states

StateMeaning
SuppliedNo trouble.
StrainedThe campaign reserve is draining; light morale pressure.
LowSerious morale pressure.
CriticalHeavy morale pressure; recovery all but stops.
Cut OffThe army comes apart every round.

The attacker's logistics

The attacker leaves full and produces nothing in the field. What it carries lasts a plain infantry force about half a day. A siege train runs dry much sooner than the soldiers escorting it, so bear that in mind when you plan a long siege.

Today there is exactly one way to renew it: send fresh troops. A force that arrives brings its own campaign supply, but only in proportion to its share of the army. A handful of men joining a large army renews nothing; in a long siege, sending reinforcements at intervals feeds both the line and the supply better than sending everyone at once.

What you bring changes what you burn

What you are carryingSupply burden
Infantry, ranged, cavalryNormal
Siege enginesThree times — they want a road, a team and a cart
Support unitsHalf

The defender's local logistics

The defender is inside a working city, and the city gives its garrison something every round. Production rises with the buildings' levels. If you are defending, the levels of the Arsenal and the Siege Workshop decide how long your garrison can keep firing.

The Warehouse plays no part in this: a store room turns out nothing for a garrison in the field.

Which building gives what

BuildingWhat it gives
ArsenalArrows, sling shot, bolts
Siege WorkshopStones
Town HallRations — the garrison's general supply

The figures come from the game's own content. Balance updates can move some numbers; the rules themselves are as written here.