The 412th Cadian is a regiment of the Imperial Guard's Cadian Shock Troops raised from the Fortress World of Cadia. The 412th is the Imperial Guard regiment that fought on the Ice World of Lorn V in Dawn of War: Winter Assault under the command of General Sturnn.
The 412th Cadian Regiment participated in the Imperial campaign on Lorn V under the command of General Sturnn. General Sturnn and the 412th Regiment land on Lorn V, an Ice World ruled by Chaos Space Marines from the World Eaters Traitor Legion's warband known as the Blood Legion of Khorne and indigenous Orks led by the Warboss Gorgutz, intending to assist the Ultramarines already on Lorn V to get a crew from the Collegia Titanica to recover the Imperator-class Titan Dominatus, a massive and powerful humanoid war engine from the time of the Horus Heresy that is powerful enough to win many conflicts by itself. Built in ancient times over 10,000 standard years before, the construction of an Emperor Titan is an enormous undertaking requiring the efforts of many Forge Worlds, and any Titans found in the wider galaxy left from the days of the Horus Heresy are treasured relics of the Imperium. Though the Imperial Guard's beachhead hits a wall (literally) trying to retake the Planetary Defence Fortress from the Forces of Chaos, the Eldar of Craftworld Ulthwe secretly assist the 412th and disable the gate preventing their progress. Eventually the troops of the 412th rescues the Ultramarines and the Titan crew, and begins the long trek to reach the disabled Titan.
The Ulthwe Eldar, led by their Farseer Taldeer, do everything in their power to make sure their presence remains unknown, but when an Ork Mekboy with unique technology capable of sensing their teleportation appears, they are forced to reveal their presence, destroy the Ork, and teleport away. Too badly damaged to accomplish their original goals following their combat with the Orks, Taldeer is forced to reveal herself and openly ask Sturnn for assistance. Sturnn agrees, and the Orks are pushed back.
In the aftermath of the combat against the Greenskins, Taldeer reveals that she does not care about recovering the Titan, but instead her goal is the destruction of the Necrons who hibernate underneath the planet's frozen surface, for Lorn V is also a Necron Tomb World. Over 60 million standard years before, the ancient xenos species known as the Necrons had chosen to hibernate deep beneath their Tomb Worlds across the galaxy for millions of years, and now they are awakening. Taldeer explained that she could not allow the Necrons to escape from Lorn V, because if they do, they will cause untold damage to the surrounding star systems and potentially to her own Craftworld before being stopped. The two factions ally, but both know their goals are mutually exclusive.
General Sturnn assists the Ultramarines in getting the Titan's crew past the uneasy alliance of Orks and the World Eaters warband on Lorn V into the safety of a waiting psychic shield, preventing their enemies from following them directly to the Titan. However, Taldeer and her Eldar are trapped with the Orks and the Traitor Marines of the Blood Legion, and she tells Sturnn behind the shield that he cannot defeat the Necrons without her. However, Sturnn laughs off her prediction with the typical Imperial arrogance shown towards xenos. As he will not risk his men for hers, Sturnn and the 412th Cadian Regiment march on to their goal, while the Eldar are butchered a few feet away from them by the Traitor Marines and the Greenskins.
Upon reaching the Titan, the Ork/World Eaters alliance known as the Forces of Disorder descends on the Imperial encampment protecting the Titan. The crew begins to work, but they require a massive amount of energy to power-up the Titan's ancient systems, and Sturnn is forced to protect the Titan, several Plasma Generators, and a nearby Imperial encampment of survivors from the Forces of Disorder. Although the Titan is too badly damaged to move until extensive repairs can be carried out, its now-operational weapons easily dispatch the Orks and Chaos Space Marines. However, the massive release of power causes the Necrons to fully awaken, and they butcher the remaining forces of the Ork/World Eaters alliance. Beginning their slow march to destroy the only living souls left, the Imperials, they nearly succeed before the Titan's new crew is able to destroy the Necron Monoliths using the Titan's weapons. Ultimately, the Cadian 412th and the Ultramarines are successful in repairing the Titan, destroying the Ork/World Eaters alliance, and destroying the Necrons before they escaped from the planet, but at the cost of the lives of Farseer Taldeer and her Eldar. This is no way bothered Sturnn or the Ultramarines, who believed the Eldar to be untrustworthy xenos.
- Dawn of War - Winter Assault (PC Game)