Sieges

From Imperium Sine Fine Wiki

Sieges work on the same morale-and-organisation foundation as regular field combat — but with a settlement standing in for an army, stone walls instead of armour, and a single besieging force pressing against a defender who has nowhere to retreat to.

Settlement Organisation

Like an army, a settlement has an organisation value ranging from 0 to 100, representing the garrison's preparedness and will to keep resisting. Unlike an army's organisation, a settlement's is only ever relevant during an active siege — outside of that, it simply recovers passively over time and otherwise has no bearing on anything. A settlement that's never been attacked never needs to think about this stat at all.

The garrison defending a settlement always fights at maximum Combat Readiness and automatically uses the Garrison strategy — there's no equivalent here to an army running short of equipment or choosing a tactical posture. The walls and the defenders behind them are simply as ready as they're ever going to be.

Organisation Drain During a Siege

A besieging force drains the garrison's organisation using the same morale principle as a field battle — the attacker's Shock Value measured against the defender's Resolve — but unlike a battlefield engagement, there's no initiative roll deciding who presses harder. The siege simply grinds on, round after round, for as long as the attacker remains outside the walls.

Siege Engines Against Settlements

Siege engines exist almost entirely for this moment. In open-field combat their psychological presence is real but modest; against a settlement, it's deliberately outsized. Rather than being averaged into the rest of the attacking army — which would dilute a handful of engines into near-irrelevance against a thousand soldiers — their Shock Value is calculated separately and added on top of everything else:

Total attacking SV = (average SV of all non-siege troops) + (average SV of siege engines × multiplier)

The multiplier itself depends on whether certain Troop Traits are active:

Source SV Multiplier vs Settlements
Baseline ×2
Bombardment trait (Siege Engine slot) ×3
Siege Masters trait (Engineer slot, requires 100+ Engineers) ×4

This is why a siege train of even ten engines can meaningfully shake a garrison's nerve regardless of how large the rest of the besieging army is — see Troop Traits for both traits in full.

City Walls

Walls are the garrison's single biggest defensive advantage, and their effects stack — a heavily fortified settlement benefits from every layer of protection simultaneously, not just whichever is strongest:

Wall Level MV/RV/AV Bonus Garrison RSV Multiplier Organisation Drain Rate
No walls — ×1.0 50% of base
1 +2 ×1.3 40% of base
2 +4 ×1.3 40% of base
3 +6 ×1.6 30% of base
4 +8 ×1.6 30% of base
5 +10 ×2.0 20% of base

These three columns work together, not as alternatives:

  • The MV/RV/AV bonus is added directly to the garrison's combat stats, exactly like any other modifier.
  • The RSV multiplier boosts the garrison's effective Resolve before the moraleCV calculation even runs — a higher Resolve naturally produces a lower moraleCV for the attacker, which in turn produces a gentler organisation-drain multiplier through the normal curve.
  • The Organisation Drain Rate is then applied as a further, independent reduction on top of whatever drain that moraleCV calculation already produced.

The combined effect compounds significantly at higher wall levels. A Level 5 wall doesn't just make the garrison twice as resistant to fear — it also cuts whatever drain does get through by a further 80%. Between the two layers, sieging a maximum-walled capital is a fundamentally different undertaking to sieging an unwalled border settlement, even against an identical garrison and an identical attacking force. This is precisely the intent: walls should buy a defender real time, not a token discount.

Capturing a Settlement

A settlement falls when either of two conditions is met: its garrison is reduced to zero troops, or its organisation reaches zero. The two represent genuinely different endings — being physically overrun, or the garrison's will simply breaking before the last soldier falls. Either way, the outcome for the settlement is identical:

  • Province Development Level decreases by 1.
  • 50% of all workshops are destroyed (rounded down).
  • Any workshops that survive become inactive.
  • City walls are reduced by two levels.
  • The Governor is killed.
  • All outposts controlled by the settlement transfer to the new owner.
  • The settlement suffers population loss.

A garrison that breaks from morale collapse rather than being physically wiped out still loses its surviving troops in the process — there's no escape once organisation hits zero, only a difference in how the fall actually happened.

Special case — Mevaro: rather than capturing a settlement outright, Mevaro forces destroy villages entirely, and raid larger settlements rather than occupying them — a raid simply destroys a single workshop and moves on.

See also