|Status||Decisive Pan-Pacific Empire|
|Imperium of Mankind||Pan-Pacific Empire|
|Commanders and Leaders|
|Orend Ymoro||Vuthros Khan|
|Second Legion (approximately 2000 Space Marines) supported by elements of the Imperial Army||Pan-Pacific troopers|
|Second Legion suffered over 50% casualties||Minimal losses|
|Second Legion decimated and weakened by radiation|
The Dalvan Atrocity was a nuclear attack perpetrated by the Pan-Pacific Empire during the Unification Wars. Their victims, the Emperor's Second Legion, took massive casualties and their gene-seed was weakened for years.
Nathaniel Dume's sprawling Pan-Pacific Empire was one of the Emperor's great rivals for mastery of Terra. For a time, direct conflict was avoided as the Emperor's armies conquered weaker techno-barbarian realms, but eventually hostilities broke out. The greater part of the fighting was done by Thunder Warriors and the men of the Imperial Army, but battling the might of Dume's realm still required the commitment of most of the nascent Space Marine Legions. The Legions primarily undertook special missions, such as seizing the strategic Dalvan Redoubt.
Commanding the Dalvan Redoubt was Vuthros Khan, one of Dume's most loyal and devoted henchmen. Khan's loyalty was guaranteed by the polite imprisonment of his family in the fortified palace of his master, though there is little evidence to suggest that the commander plotted any treachery. His posting at Dalvan steeled an already daunting fortification.
The Emperor considered sending Hektor Cincinnatus and First Legion to take Dalvan, but Gufarnus Altmakar lobbied for the Second taking the mission instead. Altmakar noted that the Dalvan Redoubt likely had a substantial underground complex and suggested the Orend Ymoro's success in the Cleansing of Calverna made him a natural choice for reducing the fort.
Ang-Quos, one of the valiant brothers of the Sacred Band, led the first battalion of Legionnaires against the Dalvan Redoubt. His command was utterly annihilated in the bright flash of Vuthros Khan's rad-missiles A supporting battalion under command of Lygrammon were burned and poisoned by radiation - those who survived suffered painful, lingering deaths after the battle. Even the third battalion, led by Pluthach, and Orend Ymoro's command section were burned and poisoned, though swift treatment by Legion Apothecaries limited deaths by radiation.
To their lasting honour, those of the Second Legion who had received lethal doses of radiation formed up under the command of Lygrammon and went into battle for the redoubt alongside the men of the Imperial Army. It soon became clear that Vuthros Khan's command had been stripped of troops, and the Pan-Pacific commander fought for only a few hours before requesting terms. After accepting Khan's surrender, fearless Lygrammon signalled Orend Ymoro that the honour of the Legion had been preserved and then lay down to die.
The casualties suffered at Dalvan were a great blow to the Second Legion, but worse still were the gene-seed defects that began to crop up in the wake of the atrocity. The Emperor commanded that Second withdraw from the field and put his gene-wrights to work on a solution. For several years, Orend Ymoro and his men wondered if they, like the Fifth Legion after the San Angelus Incident would become an afterthought among the Space Marines. But their salvation was secured with the Pacification of Luna. Pallas Eugenesis developed a method for stabilising the Legion's gene-seed and was hailed by Ymoro as "the mother of the Legion".
Interestingly, Vuthros Khan was not executed for war crimes. An Imperial tribunal accepted Khan's claim that he had carried out his orders under threat of violence to his family. Rather than an immediate death sentence, the Pan-Pacific commander was given the choice of death or taking a Warrant of Trade. Khan became a Rogue Trader and if his deeds in the Great Crusade did not atone for the blow to Second Legion, they were still of great value to the expanding Imperium.