Changes

[[Image:IV Legion.jpg|thumb|right|220px|Unification Wars-era Iron Warrior{{Fn|20e}}]]

===Origins===

The Legion continued to distinguish itself in the conquest of the [[Sol System]] during the early days of the [[Great Crusade]], winning honours in many battles, most notably in the [[Mehr Yasht]] campaign on [[Venus]], where the IVth Legion was commanded by the Emperor himself to defeat the deadly [[Litho-Gholem]] armies of the [[War Witches]]. In light of their early successes, the Legion was given first access to new equipment being delivered from [[Mars]]. The Legion led the [[8th Expeditionary Fleet]], which distinguished itself in many campaigns. However, the Legion did not adapt their tactics to the new realities of the expanding Crusade and was called unimaginative by other [[Space Marine Legion]]s and by [[Horus]] himself. Horus however was impressed by their stubbornness and would use the Legion to fight inglorious but vital campaigns of attrition. They soon became known as the workhorse Legion, relied upon for their tenacity and to follow orders to the letter. It was during this time that the Legion began to spread itself out, garrisoning many worlds and fighting many smaller campaigns across the expanding [[Imperium]].{{Fn|20a}}

Worse, their "typecasting" as siege engineers or garrison troops set them apart from their brother Legions and made them feel increasingly marginalized. In particular they were aggrieved by the [[Imperial Fists]], whose [[Primarch]], [[Rogal Dorn]], often boasted about the impregnability of the defences they had constructed around the [[Imperial Palace]] on [[Terra]]. Perturabo was not the only Primarch who found his brother Dorn boastful and arrogant, but Perturabo was unable to let the insults to himself and his Legion pass, and these continued to fester in his heart.{{Fn|1c}} Likewise, [[Corax]], the Primarch of the [[Raven Guard]], made little secret of his contempt for Perturabo and his Legion, dismissing them as stolid attritionists, anathema to Corax's own concept of fluid, hit-and-run warfare.{{Fn|19}}

=== The Turning Point ===

After this incident, Perturabo and his Iron Warriors found themselves trapped by the singularity in the heart of the [[Eye of Terror]]. In a desperate gamble, their fleet dove straight into the heart of the Eye of Terror, and were transported far across the [[Warp]] to the [[Tallarn]] System. Once arriving at Tallarn, Perturabo was made aware of the [[Cursus of Alganar|Black Oculus]] (also known as the ''Cursus of Alganar'') hidden beneath the planet, and he immediately drew up plans to [[Battle of Tallarn|acquire it]].{{Fn|23}}

After Tallarn, the Iron Warriors were assigned to guard worlds to the rear of [[Horus]]' front that since the death of the [[Ruinstorm]] were now threatened by the advance of the [[Ultramarines]]. Many of these worlds served as the Traitor's chief supply line. Overextended, under-supplied, and engaging in thankless bitter sieges against the forces of [[Roboute Guilliman]], the Iron Warriors took heavy losses and found themselves in a situation similar to that of the [[Great Crusade]].{{Fn|26}} This situation was interrupted when [[Perturabo]] received orders to find [[Angron]] and muster at [[Ullanor]] in preparation for the [[Siege of Terra]]. Despite having to abandon large amounts of warriors and worlds for which they bitterly bled for many years, Perturabo dutifully obeyed. Though many Iron Warriors were lost in the ensuing redeployments, Perturabo succeeded in arriving at Ullanor with Angron and his [[World Eaters]].{{Fn|26}} During the Siege of Terra, Perturabo became the face of Horus' war to the loyalists, engaging in the ultimate siege against his rival brother Rogal Dorn. The Iron Warriors led the assault against the [[Lion's Gate Spaceport]] and [[Gorgon Bar]] during the battle.{{Fn|52}} Following the setback at the [[Saturnine Wall]], Perturabo began to despair over the state of his allies. All save he and the Iron Warriors had by now fully fallen to Chaos, and with his warriors marched all kinds of [[Warp]] abominations. Perturabo realised that the war was no longer one of Legion vs. Legion and the ultimate test against his brother Rogal was now tainted. The final straw for Perturabo came after Horus informed Perturabo that he was to disperse his Iron Warriors amongst the various warzones and that his position was to be taken over by [[Mortarion]] and the [[Death Guard]]. Finally having had enough, Perturabo ordered the Iron Warriors to evacuate Terra and withdrew to the ''[[Iron Blood]]''.{{Fn|70}} Some Iron Warrior contingents refused to abandon the campaign or were just left behind by their comrades, and would keep fighting on Terra until the siege's conclusion.{{Fn|89}}{{Fn|90}}

From the time before the [[Horus Heresy]], the '''Unbreakable Litany''' has been a meditative chant and battle-cry for the Iron Warriors, used by [[Perturabo]] himself:{{Fn|14c}}

==Gene-Seed==