The 9th Legion was formed in 3145, by an Imperial Decree by then Emperor Hender Saik Duval, as an Imperial Special Operations unit. It was tasked with furthering the interests of the Emperor by overt and covert military action, and the defence of Imperial space. Originally headquartered in Facece, the unit was moved to Kamadhenu following tension with the regular Imperial Navy, who found its irregular (but highly effective) methods irksome. It continued to operate in a special operations role, and saw several battle honours added to its colours. All actions of the 9th are still highly classified, but it is rumoured that every major conflict has seen the unit involved.

As a result of the sacrifices of the 9th, and the distinction with which it served, Emperor Hesketh Duval granted it the system of Malaikudi as headquarters in 3218. Around this time, the existence of the unit was publicly acknowledged, for the first time, in a session of the Imperial Senate. Currently, the 9th continues to operate as a special operations unit, and in addition is often tasked with protecting Imperial border worlds from Federal incursions. Due to its nature, the 9th has often had individual Inquisitors of the Chapterhouse of Inquisition among its ranks, and it is rumoured that this is currently the case. It also has strong links with Lavigny's Legion, and the two units have fought together on several occasions against the enemies of the Empire.