The Battle of Tallarn

Tallarn is often squeezed down to “a lot of tanks in the sand”. The canon of French and Black Book VI is broader. First comes Exterminatus: a world that cannot be left behind as a living rear. Then come years (in a number of summaries the campaign is stretched out; in the atlas the peak is 010.M31) of armoured warfare, in which Astartes are rare and the Excertus machines and the IV’s armoured companies are counted in thousands. Why does Perturabo stay so long? The sources agree that something lies beneath Tallarn that he needs personally (an artefact or data — the wording varies, and the canon says nothing more specific). On the map Tallarn is a side blow relative to the arrow pointing at Terra: the IV Legion spends a resource that the Siege will need as a siege train. That is exactly why, later, Perturabo, already embittered by Iydris and Tallarn, will abandon the walls of the Palace. The loyalists “win” in the sense that Perturabo does not get what he wanted cleanly; the world remains a dead desert for ever.

The IV Legion + armour of the Dark Mechanicum against the loyal armoured formations of Tallarn, Excertus reinforcements and rare Astartes contingents. Titans are present, but tank density dominates, not the god-machines of Beta-Garmon.

Takes a bite out of Horus’s best siege Legion on the eve of the decisive theatre and cements Perturabo’s grievance.