Fifth Sphere of Expansion
Led by the revered Commander Shadowsun, the Fifth Sphere was launched into the Startide Nexus, sometime after the Great Rift's creation, when contact was made with Commander Surestrike and the remnants of the Fourth Sphere of Expansion. When Shadowsun and her forces emerged from the Startide Nexus, they were greeted by the survivors of the Fourth Sphere and welcomed to the area of space they had named the Nem'yar Atoll. Shadowsun then integrated the remnants of the Fourth Sphere into her forces and began expanding the size of the Nem'yar Atoll's domain[1a]. However this expansion was brought to a halt several months later, when a massive Death Guard armada appeared within the Nem'yar Atoll and began moving towards the Startide Nexus. Though caught by surprise, Shadowsun quickly rallied her forces against the Chaos invaders and is now engaged in a desperate battle to prevent the Death Guard from reaching the Startide Nexus and gaining a pathway to the heartlands of the T'au Empire.[1b]
The Fifth Sphere has continued on, battling the Orks of the Ful'na Nebulae as well as scattered Tyranid Hive Fleet remnants. Due to the calamities consuming the Imperium in the aftermath of the Great Rift's formation, little has been seen of the Imperium. However nearby Imperial worlds were rapidly colonized with a violent eagerness on the part of the former commanders of the Fourth that saw mass purges uncharacteristic of the Tau. Prisoners were massacred and Auxiliaries were intentionally sacrificed in battle. The Massacre of the Dul'un Lakes and the Eight Days of Infamy are the most famous episodes from this controversy. Eventually, Shadowsun and the Ethereal Council disciplined the Fourth Sphere commanders with a ritual punishment known as the Malk'la before they were returned to the ranks or sent back to the empire for re-assimilation. After a massacre and bloody Kroot uprising upon the colony of Ky'san, all auxiliaries were removed from contingents of Fourth Sphere Tau.
Despite the controversy surrounding Fourth Sphere Tau, the Fifth Sphere has continued at a formidable pace. In the span of several months several planets were occupied and transformed into thriving colonies.
- 1: Codex: T'au Empire (8th Edition)