The Perpetual Spiral was a Chapter of the Word Bearers Space Marine Legion that possessed a proud and illustrious history dating back to the earliest days of the XVIIth Legion, when they were known as the Imperial Heralds. The Perpetual Spiral Chapter distinguished itself early in the Great Crusade after bringing the worlds of the Thoth System to Imperial Compliance, then successfully defending them against the retribution of the neighbouring Anhur System, which rejected the Imperium's right to rule. Vastly outnumbered by Anhur's deviant, xenos-influenced and technologically-superior forces, the Perpetual Spiral nevertheless held all five planets, with the resolute Chapter Master Balas Silak organising a brutal defence that saw the invasion blunted. The subsequent Imperial counterattack left the hive-orbitals of Anhur in ruins, their culture eradicated.
Garrisoning worlds brought to Imperial Compliance by the XVIIth Legion became the primary function of the Perpetual Spiral, though this was said to have displeased Silak, who saw such a task as lacking in martial honour. Nevertheless, it was a role at which the Perpetual Spiral excelled, and the Chapter was praised by their Primarch Lorgar Aurelian on many occasions. The Chapter was later attached to the 47th Expeditionary Fleet, during which time it led the final assault upon the world designated Forty-Seven Sixteen. It was after this Compliance action that the Primarch took a special interest in Captain Sor Talgron. Lorgar decreed that the captain would lead almost half of the Perpetual Spiral back to the Solar System, ostensibly taking his 34th Company to garrison Terra in the name of the XVIIth Legion. More astute Imperial Remembrancers noted that the move was likely to be politically motivated -- Sor Talgron, already noted for his disregard of the XVIIth Legion's excessive reverence of the Emperor, was living proof that the Word Bearers had taken to heart the concerns expressed so forcefully by the Emperor Himself at Monarchia. Though these Legionaries presented an officious face to Imperial commanders, in reality they were secretly committing acts of sabotage entrusted to Talgron by Lorgar himself.
Chapter Master Silak fell during the fighting of the Drop Site Massacre on Istvaan V. Some suggest that it was Lorgar who had orchestrated the Chapter Master's demise, ordering his forces to where the casualty figures were likely to be highest, but such is mere conjecture. For his part, Silak saw only that his Chapter was finally gifted the singular honour of being present in the first wave of a Word Bearers' attack. Left in command of the remainder of the Perpeptual Spiral, Talgron led them in the succeeding campaigns of the Horus Heresy against the Loyalists of the Imperium. The fate of the Perpetual Spiral in the wake of the Heresy remains unknown.
- The Purge (Novella) by Anthony Reynolds