In 433.M40, the Autarch of the planet Krieg in Segmentum Tempestus declared himself independent from the Imperium and renounced the Emperor as his divine master. Krieg was then locked in civil war. Much of Krieg quickly fell to the rebels except for Hive Ferrograd which came under the command of the now infamous Colonel Jurten of the Krieg 83rd Imperial Guard. Under strict orders to not let Krieg fall but with the promise that no fleet on the scale that was needed to invade a planet was available Jurten decided that Krieg would either belong to the Emperor or to no one. On the day of the feast of the Emperors Ascension Jurten unleashed a counter attack of atomic cleansing that was to turn into a great purging. For days Krieg was engulfed in a sea of Nuclear fire. Kriegs ecosystem collapsed and the planet was engulfed in a nuclear winter. But the civil war dragged on. The survivors from Jurten's purging were forced to exist in underground bunkers or deep in the radioactive chem-wastes, as their descendants do to this day. From the self-annihilation of their home world, loyalist troops slowly retook their world inch by inch over 500 years. From this the Death Korps were born. Krieg was finally returned to the Imperial rule in 949.M40
As penance for the Autarch's heresy, the Death Korps regiments each embarked on their own quest for absolution, constantly requesting transfers to the most lethal warzones throughout the galaxy. Every soldier in the Death Korps is proud of the regiment's part in the purification of Krieg and they despise the cowardice of lesser men that would flinch from such acts. The regimental creed is to eradicate heresy and weakness wherever it is found and on numerous occasions Death Korps forces have been reprimanded for their excessive use of force and unsanctioned genocidal campaigns.
The Death Korps are fearless warriors, never flinching even in the face of sudden death, which they see as atonement for the rebellion. They see their deaths fighting in war as penance for the heresy of their ancestors. Death Korp commanders also possess this mind set and take a highly analytical approach to warfare, seeing the troops they command as a means to 'buy' victory, effectively 'spending' their men in order to grind down their opponents. This is due to their perception that the lives of their men are worth little in the Emperor's sight, so mired in sin are their souls. They are dedicated trench and siege warfare masters, and often use battalions of Death Riders, a local form of Rough Riders, which are used widely in the Imperium for flash attacks. However, the Death Riders do not ride normal steeds (as their battle brothers); rather, the Death Riders use either heavily "re-built" steeds with metal implants to increase their endurance in battle, or a totally robotic steed.
Appearance-wise, the Death Korps are similar to the Steel Legion, but wear greatcoats instead of trench coats, much darker colours, use lasrifles and the masks of their grenadiers bear a skull motif. Of all the regiments of the Guard, they are the most gloomy and dark, both in appearance and in spirit. These troops are based on the German Army of World War I and World War II. It should be noted that the regiment uses German words such as Panzer frequently. Krieg is the German word for war.
It should also be noted that Krieg raises an unusually large number of regiments for so devastated a planet. This is because of the use of cloning technology, which Krieg has been granted special dispensation to use due to the steely and determined nature of its troops and its unswerving loyalty to the Emperor. Use of this technology is generally prohibited throughout the Imperium (reasons unknown) by the Adeptus Mechanicus, the custodians of the Imperium's technological lore. This may be why Death Korp troops are so rarely seen without their characteristic gas masks.
Forge World has designed and released infantry and vehicle models for the Death Korps.