How to Read This Atlas

The atlas’s timeline runs from the Razing of Monarchia (964.M30) to the Iron Cage (019.M31). The unit is a conventional M31 year, counted from Ullanor (000.M31); Calth falls in 007.M31, the Siege in 014.M31. Within the “hot” years events are packed more densely than it seems on the scale of centuries: almost all the shooting fits into ten years.

A practical rule: do not jump straight to the Siege. Begin with 000.M31 and see how golden the galaxy still is; then Isstvan III (005.M31), the drop site on Isstvan V (006.M31), Calth (007.M31), Imperium Secundus (009.M31), Beta-Garmon (013.M31), the walls of Terra (014.M31). Those are the six frames that explain everything else.

If an event’s date is marked as disputed, read the canon note: Davin, Ullanor, Nuceria and a number of siege phases diverge between the novels and the compilations. The atlas chooses a single scale so that the routes do not break, and honestly says where the choice is disputed.

Take the Calth system in 007.M31 and keep in view only the XIII and XVII: their routes show that the XVII did not “suddenly turn up in Ultramar” but came as an ally to an announced muster — the Ultramarines were gathered at Calth on the pretext of a campaign against the orks of Ghaslakh.

The card “Battle of Calth” gives the sides and the outcome; the article on the Ruinstorm tells why a star was killed, and not only people. Do not stop at a single icon: right after Calth come Armatura (007.M31) and Nuceria (008.M31) — the same campaign, at a different speed.

If you look only at Calth, Lorgar looks defeated (Guilliman is alive); if you add the Shadow Crusade, he looks like the architect of a storm that will subtract the east from the Siege. This is how the atlas asks you to read any big name: a point plus a corridor plus the Legion’s dossier.

Fleet routes live in their own windows of time: they appear and fade by themselves as the timeline moves — the “Eisenstein” does not fly for all ten years. A practical check: keep no more than two or three routes in view, otherwise Isstvan, Ultramar and Sol merge into a single arrow that was not in the canon.

Strengths live not on the map but in the Legions’ dossiers and force snapshots: these are estimates counted in Astartes by the head, not an official ledger, and almost every one is marked as disputed. Legions II and XI are struck out. The Alpha Legion and the Thousand Sons are the most threadbare lines: do not build “precision” graphs on them.

Compare orders of magnitude, not figures: about 250 thousand for the XIII against a few thousand survivors of the XIX after the drop site (the sources give from “less than three thousand” to 4,724) — that is a fact, even if both estimates are approximate. The moment a Legion changes sides is described in its dossier: a Legion’s side in the atlas is its canonical allegiance as a whole, and it is not recoloured as time passes.

An event card always holds the date, the system, the type, the sides (Legions / factions / commanders), the outcome, the sources. Read the sides carefully: at Isstvan III the loyalists are not “the Imperium” but landed companies of the same four Legions that bombard from orbit. The outcome “Atrocity” denotes a moral category, not an operational one.

A Legion’s dossier is not a bestiary: “Speciality” and “Tactics” say how it stands on the map (the “Speartip” of the XVI — points, not lines; the IV — sieges; the V — corridors and flanking manoeuvres). A character is linked to key events: Horus without Davin and the Vengeful Spirit is a portrait without a plot. The duels (Fulgrim/Ferrus, Khan/Mortarion, Emperor/Horus) are set apart in the primarchs’ dossiers, because the operational map swallows them.

If a card disagrees with an article, the event card is right: it is closer to the source. An article is a method of reading, not a substitute for the date and the sides.

There are four modes. “Map” answers the question “where and when”. “Chronicle” unrolls the same events into a list by time — convenient for catching the density of a year that the map hides. “Legions” compares doctrines and forces. “Siege” is a separate scale: the phases of the Palace with their own windows, like the plan of a building instead of a theatre of war.

The right order of work: question → time → event on the map → dossier of a Legion or a person → article (dispute and method). The reverse — “all the novels first” — is also legitimate, but then the atlas serves as a table of contents, not an investigation.

If something does not add up (the Lion is “loyal” but not on Terra in 014), that is not a bug, that is the canon: Thramas, Imperium Secundus and the destruction of Caliban explain it. The atlas deliberately does not pull all the good ones to the walls and all the bad ones to Horus. The geography of the Heresy is the geography of delays.