Aquila - History: The Aquila is the ancient symbol of the Imperium of Man, chosen by the Emperor of Mankind Himself at the start of the Great Crusade in ca. 798.M30. The Aquila replaced the earlier Imperial symbol of an eagle's head and crossed lightning bolts known as the Raptor Imperialis that had been used to represent the Imperial forces during the Unification Wars on Terra in the 30th Millennium.The Emperor intended the Aquila to serve as the banner under which His newly-created Legiones Astartes would forge a new galaxy-spanning interstellar government for Humanity.The ancient variant of the Aquila used during the Great Crusade was known as the "Palatine Aquila." It was after the Proximan Betrayal that the then-loyal Emperor's Children Legion was granted the exclusive right to bear the Palatine Aquila, the Emperor's personal standard, in its own heraldry.This honour was bought in blood when the III Legion's XVI Cohort, assigned to the Proxima Compliance ceremonies and as an honour guard for the Emperor, fought and died to the last warrior alongside the Legio Custodes, never giving ground during the insurrectionist surprise attack on the ceremonial plaza. By their sacrifice was the wounded Emperor, who had suffered injury due to the use of a Vortex Weapon by the attackers, bought time to recover and fight His way clear of the insurrectionist trap.In recognition of this sacrifice, the standard of the Palatine Aquila so fiercely fought for that day was given to the Emperor's Children by the Emperor's own hand, to be their relic ever after, along with the right to end the Proxima revolt by Exterminatus and so repay the blood that was owed them. From that moment on, the Emperor's Children were the only Space Marine Legion granted the right to bear this sacred emblem as the executors of the Imperial will.During the time of the Great Crusade before the Horus Heresy, the two-headed eagle was blind-folded on the right side, while the left possessed eyes. The blind side of the symbol represented Mankind looking back into its past at the lessons of its history and traditions, while the sighted eagle looked into the future and the hope of the better life that the Emperor would create for Humanity.After the Heresy, as the Imperial Cult took hold of the minds of Humanity in the 32nd Millennium, the Aquila's meaning changed to represent the political union of the Imperium that had been formed between the forces of the Emperor on Terra and the Mechanicum of Mars following the signing of the Treaty of Mars.Space Marines in the wake of the Second Founding after the Horus Heresy sometimes use a different version of the Aquila on their weapons, chestplates, banners and finials. Known as an Imperialis, this ancient symbol consists of a winged skull, and harkens back to the Horus Heresy when it was used by the Loyalist Space Marine Legions and the troops of the Imperial Army in recognition of bravery and loss. Later, it became a badge of honour borne by Loyalist units during the Heresy. Now, in the 41st Millennium, it is used more to symbolise the righteous victory of the Imperium over its many enemies in general and is awarded to Space Marines as a badge of honour following a victorious battle in which they participated.The Imperialis is intended to represent the Space Marines' slightly different relationship with the Emperor than the rest of Humanity in the 41st Millennium. Traditionally, the Adeptus Astartes do not believe that the Emperor is a deity but revere Him as Humanity's greatest visionary and for the extraordinary sacrifice He made for the sake of Mankind when He defeated Horus and allowed Himself to be interred as a living corpse within the Golden Throne.The Astartes are willing to defend the Emperor's original vision of the Imperium to their last breath despite His current existence trapped somewhere between life and death.