Iron Nest Mission 15: White Shells - Solutions

Worked example: Bearing, range, charge and elevation figures below come from a sample playthrough. Enemy spawns and your Iron Nest’s position vary each run — always measure on the map and follow the in-game ballistic calculator.

Mission Critical Strategy: The Choice Is Made Before the Lanyard

Mission 15 does not present a single military objective. It asks what Iron Nest will do with the ultimate command order — and unlike every previous mission in the campaign, the thing that decides the outcome is not your aim. It is your ammunition selection, decided before you ever touch the firing lanyard.

High Command issues a final ultimatum regarding Barcelona and expects a shell on the city. You have four ways to answer, and each one resolves to a different ending:

• Deliver PRPG propaganda leaflets and the city celebrates its liberation.
• Deliver CHEM incapacitating gas and the city is subdued without demolition.
• Deliver the ATOMIC shell and the sector goes silent.
• Or refuse entirely — turn the turret on High Command itself and take the hidden mutiny ending, The Road Not Taken.

The structural consequence is that mission planning happens backwards from the ending you want. You choose the outcome first, then requisition the round that produces it, then compute the solution. Operators who drive to the finale and start improvising at the gun tend to discover they are carrying the wrong shell in the magazine.

[!WARNING] The ending is committed the moment a round lands on Barcelona. There is no undo, no reload of intent, and no way to walk a chemical strike back into a leaflet drop. Decide the path, requisition the correct ammunition, and only then open the map.

The three Barcelona targets share one ammunition problem

Look at the three city-facing options together and the preparation collapses into a single repeated drill:

Path	Target	Range	Charges
PRPG	Central Plaza	16.80 km	4 Charges
ATOMIC	Central Grid	17.00 km	4 Charges
CHEM	Government Quarter	17.20 km	4 Charges

All three sit within a 400-metre band of each other, and all three take the same 4-charge load. That matters practically: whichever city path you intend to take, the gun preparation is nearly identical, and only the bearing and the elevation differ between them. You can therefore pre-compute all three solutions in one pass, then pick the one matching the shell you actually loaded.

The mutiny path is a different mission entirely

The Road Not Taken is not a variation on the city strike — it is a separate operation grafted onto the finale. High Command Headquarters sits in Sector HQ-9 at bearing 342.0°, just 8.40 km away: less than half the range of the city targets, and in the opposite direction. Choosing it means refusing the ultimatum outright, and the retaliation does not wait politely for you to finish admiring the shot.

The path has a strict sequence, and skipping a step in it is how the run fails:

1. Recon the command bunker before committing.
2. Mark the retaliation batteries — they are the real threat.
3. Pre-calculate the solutions for both the HQ and the batteries.
4. Purchase APHE shells from requisitions.
5. Fire on HQ.
6. Immediately destroy the retaliation battery before it can answer.

Note the ordering: the reconnaissance and the pre-calculation both happen before the shot. Once HQ is hit, the run becomes a reactive engagement, and you will be doing it with whatever you already prepared. Also note that the same recon → mark → calculate discipline carries the ammunition decision with it — you cannot take this path with H that you happened to have left over.

For a full comparison of what each ending means narratively, and how the four achievement unlocks map onto these paths, see the dedicated endings guide. This page covers the mission execution; that one covers the outcomes.

Pre-Calculated Firing Solutions

Ending Path	Target	Target Grid / Sector	Turret Bearing	Target Range	Powder Charges	Elevation (θ)	Ammunition
A City in Celebration	Central Plaza, Barcelona	—	—	16.80 km	4 Charges	50.40°	PRPG (Leaflet Propaganda)
A City Subdued	Government Quarter	—	—	17.20 km	4 Charges	51.60°	CHEM (Incapacitating Gas)
The Road Not Taken	High Command HQ	Sector HQ-9	342.0°	8.40 km	—	—	APHE
A City Silent	Central Grid	—	—	17.00 km	4 Charges	51.00°	ATOMIC (Forbidden Weapon)

Step-by-Step Operator Routine

Phase 1: Pre-Fire Decision and Requisition (No Timer)

1. Receive High Command’s ultimatum and read it in full before doing anything else.
2. Decide which of the four endings you are pursuing. This is the only decision in the mission that cannot be revisited.
3. If taking a Barcelona path: requisition PRPG, CHEM or ATOMIC as appropriate and pre-calculate all three city solutions in one pass — the charges are identical, so the extra work is small.
4. If taking The Road Not Taken: recon the command bunker, mark the retaliation batteries, pre-calculate both the HQ solution and the battery solutions, and purchase APHE.
5. Confirm you are physically holding the correct round before you touch the traverse wheel.

Phase 2: Execute the Barcelona Path (PRPG / CHEM / ATOMIC)

1. Load 4 Powder Charges with the chosen shell.
2. Set the elevation for your chosen target: 50.40° for Central Plaza, 51.60° for the Government Quarter, or 51.00° for the Central Grid.
3. Traverse to the corresponding bearing and confirm against the bearing indicator.
4. Verify charge count and elevation one final time.
5. Fire. The ending resolves on impact.

Phase 3: Strike High Command (The Road Not Taken)

1. Do not fire on Barcelona at any point. This path is defined by refusal.
2. Load APHE and traverse the turret 180° back toward command HQ.
3. Bring the gun onto bearing 342.0° at a range of 8.40 km. Note how much shorter this shot is than the city solutions — this is a close, flat, precision engagement, not a long-range bombardment.
4. Confirm the pre-calculated solution for HQ and fire.

Phase 4: Retaliation Response (No Timer)

1. Expect an immediate response. Command’s retaliation battery is the actual difficulty of this ending, and it is why the batteries were marked during the planning phase.
2. Bring the pre-calculated battery solution onto the gun without stopping to re-measure. The work was done earlier precisely so that this phase can be purely mechanical.
3. Destroy the retaliation battery. Failing to finish it is the most common way this ending is lost after the HQ round has already landed.
4. Confirm the sector is clear. The ending resolves only after command’s answer has been silenced.

Phase 5: Confirm the Ending

1. Verify the ending register and the achievement unlock. If nothing appears to register, re-read the objective log before assuming the run failed — a partially completed retaliation phase is the usual cause.
2. Do not reload to experiment with a second path until the current ending has been confirmed as saved. The four paths are mutually exclusive within a run.

[!IMPORTANT] Operator Rule: In White Shells, never arrive at the gun without having already chosen the ending. The mission is not decided by marksmanship — it is decided by which round is in the breech. Pick the outcome, requisition the shell that produces it, compute the solution, and only then fire; and if you intend to refuse the order, refuse it fully by keeping the gun off Barcelona entirely.