Prefectia Campaign - Third Sphere Expansion: With the Ork invasion of the Great War of Confederation in 975.M41 defeated and a new hero risen during that conflict in the person of O'Shaserra, Commander Shadowsun, the Tau Ethereal Supreme Aun'Va knew the time was ripe to declare the Third Sphere Expansion in 997.M41 as the Imperials reckoned time. With more established Septs to draw resources from, this drive to expand the size of their realm was undertaken on a scale never before attempted by the Tau Empire.As bold and dynamic as the previous Spheres of Expansion had been, they had been confined to the dense star clusters that surrounded the Empire's homeworld of T'au. The scope of such expansions was limited -- the Tau did not have the population needed to spread further, and they had not yet fully learned to harness the full power of alien auxiliaries like the Kroot to aid their cause. Technical constraints proved a barrier as well, for the Earth Caste have constantly been seeking ways to develop starcraft with faster engines to allow them to bridge the vast gulf of empty interstellar space between star systems.Aun'Va knew that now was the time for the Tau to seize their destiny. The Great War of Confederation had served to put the Tau on a total war setting -- as the Ethereals pressed each caste for greater production and higher efficiency. The Ork invasion had proven a harsh training ground for the Fire Caste, but they had now replaced the casualties of the long, drawn-out campaign. Furthermore, many Fire Warriors and their Commanders had gained invaluable experience. They were now better trained than ever to coordinate their efforts with other Septs and with the Tau Navy. The amount of alien auxiliaries at hand for deployment to the Fire Caste was greatly increased, especially the availability of the Kroot.In order to reach those more distant systems earmarked as desirable by advanced scouts, the vast armadas of Tau starcraft had been outfitted with the latest Earth Caste modifications. The ships' propulsion systems were upgraded so that when magnified by Impulse Reactors, the new ZFR Horizon Accelerator Engines could obtain faster speeds -- propelling Tau starcraft forwards at hitherto unthinkable velocities just shy of the speed of light itself. To further lessen the burden on those space-faring craft with the longest journeys, the Earth Caste had outfitted transport craft with large stasis chambers -- allowing Hunter Cadres or whole commands to shift to far distant battle zones Terran months or years away without actually aging a day in the process.While all Septs sent ﬂeets to aid in the great expansion, the largest gathering of force was at the northern and western extremes of the Tau Empire. There, massed at the ports and orbital docks of Dal'yth, Sa'cea, and Vior'la, were huge flotillas. In addition to the fighting classes of starships, the Tau Navy also provided whole armadas of transports to carry armies, colonists, pre-fabricated domes, Tau Drone builders and all manner of equipment. This massive force was to be led personally by Commander Shadowsun -- the newly appointed highest-ranking Fire Caste officer. Their course was to cross the Damocles Gulf, travelling past the Gri-lok asteroid fields. Target destinations had been meticulously planned out -- all planets and moons desired for colonisation were well-marked on the fleet's holomaps. Those worlds that had indigenous populations had already had many preemptive visits by Water Caste traders and ambassadors in order to explore possibilities for a peaceful annexation.Some of the planets branded for absorption into the Tau Empire were worlds that belonged to the Imperium of Man. In these cases, Aun'Va's timing of the Third Sphere Expansion could not have been better. Water Caste agents and Gue'vesa -- human helpers who had sworn loyalty to the Tau and the Greater Good -- confirmed what the Earth Caste had already reported via intercepted Vox transmissions: due to wars elsewhere, the number of Imperial defenders at the borders of their territory was much reduced.Some Imperial planets, those open to bribery or idealists that wished to escape the pressing yoke of servitude to an overbearing tyrant, lay down their arms at their first opportunity -- welcoming Water Caste ambassadors with pledges of cooperation. Most human worlds, however, rejected Tau overtures -- mistrusting all aliens or perhaps simply more frightened of the repercussions they would suffer at the hands of their own race. For those frontier worlds that resisted, Shadowsun and her armies swept down in a series of precision strikes. The human Planetary Defence Forces proved insufficient to even slow the Tau down, much less them hold off.The northernmost sector past the Damocles Gulf was soon wholly in Tau hands, while to the galactic west, the sectorsadjoining the Red Sun Systems were cleared of Hrud, Orks and rebel humans. Fleets of Water Caste IndigenousInhabitants Liaison conclaves were deployed to begin their long integration process for those aliens that wished toseize upon the enlightenment that was being offered. The Earth Caste, eager to exploit their new domains, was alreadydropping producer domes upon recently-seized planets rich with resources. In order to keep the drive going outwards,the Tau needed to establish fuel sources closer to the front lines of expansion. Linked back to the Tau Empire by long chains of relay comms, the expansion had already claimed dozens of new worlds -- yet this was only the start.