Horus Heresy · atlas

Investigation · 4 steps · 001.M31 — 007.M31

The Two Truths of Prospero

Nikaea, the breach of the Webway, a substituted order: how to read the extermination of the XV

On the cover: V White Scars

Prospero is at once the saving of the Emperor from a warning and the extermination of a civilisation on a forged order. The atlas holds both truths and does not choose who is “right”.

Step 1 of 4 · 001.M31

Nikaea as disarmament

The ban on the Librarius corps strikes the one Legion whose doctrine is the warp as a craft.

At the Council Magnus defends the right to explore the warp and loses: the Edict of Nikaea disbands the Legions’ Librarius corps, forbids the primarchs sorcery and establishes the chaplains. A political event whose military consequences arrive three years later, on Prospero. To read Nikaea as a “philosophical dispute” is to fail to see that the XV was disarmed before the battle.

Event: Council of Nikaea · System: Prospero

How to look in the atlas
  • “Search” → “Nikaea”; the card is tagged with the type “Politics” — there are few such on the timeline, and they are the forks.
  • The dossiers of Magnus and Russ side by side: the grievance of the one and the future executioner’s role of the other begin here.

Canon note

  • The Council is dated to 001.M31, the Burning of Prospero to 004.M31: hence the “three years” before the blow.

Sources

  1. A Thousand Sons (G. McNeill)
  2. Prospero Burns (D. Abnett)
  3. The Horus Heresy Book VII: Inferno

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Step 2 of 4 · 004.M31

The breach: rescue as catastrophe

Magnus cries out to the Father through the warp about Horus — and tears the Emperor’s principal work.

With forbidden sorcery Magnus breaks through the psionic wards of the Imperial Webway project beneath the Palace, and daemons pour into the tunnels. From that moment the Emperor is chained to the Golden Throne to hold the breach: the War Within the Webway begins — ten years before the Siege. The warning about Davin costs the Imperium its future. Without this frame Prospero reads as “just a burned world”.

Event: Magnus’ Folly: the Webway Breach · System: Terra

How to look in the atlas
  • Slider at 4.35: Terra is not burning on the outside — it is the project that burns. There is no flash on the map, but the event is in the “Chronicle”.
  • Follow the chain: 4.35 the breach → 5.5 the War Within the Webway → 14.06 the Unspoken Sanction → 14.587 the defeat of Magnus.

Sources

  1. The Master of Mankind (A. Dembski-Bowden)
  2. A Thousand Sons (G. McNeill)

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Step 3 of 4 · 004.M31

The Burning

The VI, the Custodians and the Sisters of Silence against the XV. Tizca ceases to exist as a culture.

The Space Wolves, Legio Custodes and the Sisters of Silence fell upon Tizca, the “City of Light”, punishing the Thousand Sons for breaking the Edict. Magnus, aware that his sorcery had doomed the Legion, barely resisted; Russ broke his spine. The doomed Magnus struck a bargain with Tzeentch and carried the survivors to the Planet of the Sorcerers in the Eye of Terror. Two books — two truths: A Thousand Sons and Prospero Burns. The atlas sets one date and both sides. The loyalists lose the XV forever even before Isstvan III.

Event: Burning of Prospero · System: Prospero

How to look in the atlas
  • The card for the burning: both side columns; the “Special forces” chips — the Custodians and the Sisters of Silence.
  • The date-confidence tag is “disputed”: the FW date-fraction 734.004.M31 and Lexicanum give 004.M31; the Fandom grouping “005–006” is not a real dispute over the year.

Disputed in the canon

  • The dating of the burning of Tizca is marked as disputed, but the divergence is illusory: the Forge World fractional date 734.004.M31 and Lexicanum agree on 004.M31, while “005–006.M31” is merely a rough grouping of rows in the Fandom table, not an independent version. The atlas holds to 004.M31 — before Isstvan III, as the order of events requires.

Sources

  1. Prospero Burns (D. Abnett)
  2. A Thousand Sons (G. McNeill)

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Step 4 of 4 · 007.M31

The second battle: Prospero without the Thousand Sons

Prospero flares up a second time — but the fighting there is between the White Scars and the Death Guard, not the VI and the XV.

Jaghatai Khan, guided by a projection of Magnus, met Mortarion in single combat, but the clash left no decisive wounds. Mortarion withdrew, and Khan set a course for Terra, having finally settled his loyalty.

Event: Second Battle of Prospero · System: Prospero · Duel: Jaghatai Khan against Mortarion

How to look in the atlas
  • The card for the second battle: the columns hold the V and XIV — neither the VI nor the XV.
  • The duel card “Khan against Mortarion” on Prospero; their second meeting will be at the Lion’s Gate, at 14.574.
  • “Chronicle” 0 → 4.6 → 7.6: the XV disappears from the loyalists and returns, diminished, to the traitors.

Canon note

  • In the Second Battle of Prospero the White Scars of Jaghatai Khan and the Death Guard of Mortarion fight (Lexicanum: Second Battle of Prospero); the battle is a consequence of the attempted coup by Hasik Noyan-Khan, and Mortarion withdrew. The VI and XV Legions are not in it, and Magnus does not fight: only his projection guides Khan.

Sources

  1. Scars (C. Wraight)

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What to remember

  • Nikaea disarms the XV three years before the blow.
  • Magnus breaks the Webway while trying to warn of the treachery — and chains the Father to the Throne.
  • Russ carries out what he takes to be the Father’s order; the text was substituted by Horus.
  • The Second Battle of Prospero is no longer about the XV: there it is Khan and Mortarion.

Sources

  1. A Thousand Sons (G. McNeill)
  2. Prospero Burns (D. Abnett)
  3. Scars (C. Wraight)
  4. The Inferno (Forge World Black Book VII)
  5. Lexicanum: Second Battle of Prospero
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