Second Sphere Expansion - Second Sphere Expansion Timeline: The T'au have developed their own mode of timekeeping based on the annual cycle of their homeworld of T'au around its star, a unit called a tau'cyr. Except on Human planets that are still in the process of being subsumed into the T'au Empire, the T'au do not use the Imperium's dating system. However, for ease of translation, it has been employed here:Second Sphere Expansion Begins (018.M39) - The Ethereal Supreme, Aun'Wei of the Whispered Wisdom, gives the signal to begin the long-planned Second Sphere of Expansion. Aun'Wei's famous speech is well remembered, ending with "the nod that launched a million ships." With new advances in propulsion technology and an already established interstellar empire, the second expansion is marked by more contact with aliens and larger wars.A New Ally (053.M39) - The planet Vespid is absorbed into the D'yanoi Sept. The insectoid Vespid species had long been courted by the Water Caste -- but little was established save for crystal trade agreements. Within days of the Ethereals' involvement, the Vespid Strain leaders convert wholeheartedly to the cause of the Greater Good.N'dras Colonised (383.M39) - Despite Earth Caste reservations from those who want to study inexplicable sensor readings, the planet N'dras is chosen by the Ethereal Council as the prime world of a new Sept.Steady Advancement (576.M39) - Improvements to anti-gravitic motors and new T'au Battlesuit technology (the T-series prototypes) help the Fire Caste complete the annexation of Tash'var Sept.Mistaken Identity (876.M39) - War is declared upon the cruel raiders victimising the new colonies of Ke'lshan. Believing they have tracked their foes down, the T'au instead destroy the Aeldari Maiden World of Lilarsus. Further relationships between the T'au Empire and the Asuryani of the craftworlds continue to be strained.Vior'la Triumphant (600.M40) - A massive Ork fleet invades the Vior'la Sept, but is defeated in a masterful campaign. Vior'la annually passes through a gap between its two stars, a time called the "Trial by Fire." This natural event causes deadly plasma storms to ravage the planet, whose inhabitants survive by closing protective domes around their cities. The Ork Warlord Garskrak and his invading army are lured into this deadly plasma storm where they were utterly destroyed by the raging plasma radiation.Mass Migration (896.M40) - The greatest Water Caste envoy, Por'O Dal'yth Kais Twi Lui'tan, better known as the "Golden Ambassador," leads the effort to recruit alien worlds into the T'au Empire. During this period the Thraxians, Greet, and Formosians are welcomed into the fold. The Hrud and Arache reject the proposals and are driven out of the region.A Legend is Born (651.M41) - The birth of Commander Puretide, the pride of the Dal'yth Sept. His brilliant campaigns later conquer half a dozen star systems for the T'au Empire. Under his authority, the T'au envelop those who can be embraced, seize what can be conquered and obliterate those who defy the Greater Good.The Once and Future Master (731.M41) - The now-elderly Commander Puretide is urged to view the new colonies across the Damocles Gulf before retiring. While inspecting a colony, Puretide is wounded during a raid. Unable to walk again, the most revered of T'au military leaders spends his remaining years atop Mount Kan'ji, on Dal'yth, where he is kept alive for many more solar decades using advanced T'au biomedical technology. Only those who attain perfect scores at the Fire Caste academies are sent to sit at Puretide's hover-throne and learn his wisdom. Thanks to Earth Caste holographic technology creating interactive copies of Puretide's teachings, this tradition is still maintained, although few students are deemed worthy of receiving this high honour.Arkunasha War (733.M41) - The Arkunasha War is a Terran-decade-long conflict in which a populous T'au colony is besieged by Orks. It is especially notable for the rise of the brilliant Puretide prtotégé named Commander Farsight.Damocles Gulf Crusade (742.M41) - The T'au Empire comes under attack by an armada of the Imperium's warships on an Imperial Crusade to reclaim their long-neglected territory in the Eastern Fringe. It is a bloody campaign, which is finally stymied at Dal'yth Prime. The retreat of Imperial forces to face the Tyranids of Hive Fleet Behemoth marks the end of the Second Sphere Expansion.