Taros was an Imperial frontier Mining World in the Eastern Fringe of the Segmentum Ultima and Tau Water Caste diplomats had long been in contact with its Imperial Planetary Governor, trading luxury goods for the planet’s rare heavy metal strategic mineral resources. Both sides had benefited from the arrangement, but it was just the first step in the Tau’s long term plan to eventually incorporate the planet into their expanding Empire. When the Planetary Governor’s illegal contact with the Tau was discovered by the Administratum in the course of a desire to speed up Imperial mining operation to increase industrial production in preparation for the defence of the Cadian Gate during Abaddon's 13th Black Crusade, the Imperium's response was swift and powerful. A Space Marine strike forcecompri