The Horus Heresy
Commanded during the last stages of the Great Crusade by Princeps Esau Turnet, it had already gained a fearsome reputation among the warriors of the 63rd Expeditionary Fleet, and was an awe-inspiring sight to behold as it strode over the battlefield. Its name means "Day of Wrath".[Needs Citation]
When the Warmaster Horus betrayed his loyalist forces at Isstvan III, the Dies Irae was caught in the virus bombardment but Princeps Turnet had the gigantic machine sealed against the deadly vapours and his crew watched on in horror as the world died around them, including many of the Death Guard Astartes they had been supporting only moments before. As the secondary firestorm erupted, without the benefit of cooling systems and ventilation the crew were very nearly overcome by the intense heat, but when the flames died and the extent of the Warmaster's plan became apparent, Turnet ordered his crew to attack the remaining Death Guard that had hidden in sealed bunkers below the enemy front lines.[Needs Citation]
Initially, Titus Cassar refused to carry out the orders and attacked Turnet with his sidearm autopistol, but he was killed by his former friend and ally Aruken, who made his own ambitions quite plain. The Dies Irae went on to attack the remaining loyalist forces in the capital city.[Needs Citation]
As the siege of the Emperor's Palace ground on during the Horus Heresy, Horus ordered the Legio Mortis and the rest of the Traitor Titan Legions to breach the walls of the Palace whatever the cost. It was the Dies Irae that was the first to break the walls, throwing back the defenders that swarmed to protect the breach and allowing the hordes of daemons waiting for an opening to swarm in. This action earned it immortal infamy within the Adeptus Titanicus and its destruction was considered to be worth the cost of an entire Titan battlegroup.[Needs Citation]
Dies Irae was last seen serving as part of the Iron Warriors force that attacked the fortress of Tor Christo, during the Siege of Hydra Cordatus.[1a]. Unlike the titan that had breached the walls of the Imperial palace so many millennia ago, the Dies Irae had been twisted and mutated drastically by the warp, increasing its already formidable strength with the dark power of Chaos, notably adding a tail with a large spiked wrecking ball[1a].
At the head of its own traitor Titan group, the Legio Mortis, it led the assault on the fortress and immediately drew the attention of the defending Legio Ignatum led by Princeps Fierach of the Warlord Battle Titan Imperator Bellum[1b]. Fierach abandoned the post he was defending and led two more Reaver Battle Titans to go head to head with the Dies Irae but the loyalist titan group were decimated by the return fire which destroyed both Reaver Titans and left the Imperator Bellum severely damaged with a failing reactor. Fierach moved his Warlord into close combat with the Dies Irae and attempted to inflict enough damage to the body section of the Imperator to leave it open for a killing blow when his Titan's plasma reactor finally failed and overloaded.[1c]
Although the large explosion from the Warlord's reactor was not enough to destroy the Dies Irae, it did seriously damage the lower section of the traitor Titan, leaving it immobilised and seemingly unable to take further part in the battle aside from firing ranging shots at the fortress wall.[1d] [1e] Scaffolding was erected around the Dies Irae in an attempt to repair the damaged Titan to allow it to return to the battle and eventually, to the surprise of the defenders, the Dies Irae was able to move again.[1f]
Princeps Daekien, in charge of the remaining Titans and in control of the Warlord Titan Honoris Causa led the Reaver class Titans Armis Juvat and Pax Imperator against the Dies Irae. Again the Dies Area retaliated with heavy firepower, destroying both Reaver Titans, but this time Daekien was able to punch through the Dies Irae's crudely-repaired armour covering the wound Princeps Fierach had opened with his Titan's battle claw and breach the Imperator's reactor. Both titans grappled with each other, fell to the ground and were both destroyed as the molten fluid from the breached reactors consumed their remains.[1g]
Whether Moderati Aruken or Princeps Turnet were still in control of the Titan at the time of its destruction is unknown, but it is highly possible that they had been twisted by the same powers that warped their once-noble Titan.
- 1: Storm of Iron (Novel) by Graham McNeill
- Horus Rising (Novel) by Dan Abnett
- False Gods (Novel) by Graham McNeill
- Galaxy In Flames (Novel) by Ben Counter