|Location =[[Prefectia]]

|Outcome =Tau victory

|Strength1 =[[Prefectia Campaign_#Order of Battle|See Order of Battle]]

|Strength2 =[[Prefectia Campaign_#Order of Battle|See Order of Battle]]

The '''{{PAGENAME}}''' was a confrontation between the [[Imperium]] and [[Tau Empire]] in the closing years of the [[41st Millennium]] during the Tau [[Third Sphere of Expansion]].{{Fn|1i}}

Following the decisive Tau victory at the [[Battle of Mu'gulath Bay]], Tau Supreme Commander [[Shadowsun]] immediately began planning a new general offensive, this time aimed at the [[Dovar System]]. She became even more motivated following her defeat at the [[Battle of Voltoris]], determined to regain the initiative. The Dovar System included the [[Gilded Worlds]], a system impossibly rich in precious metals. The Imperial world of [[Prefectia]] was the ideal staging ground from which the Tau could engineer the fall of the entire Dovar System. However Prefectia was rich in Geomagnetic energy and on the borders of the [[Eastern Fringe]], and thus Imperium had turned the world into a planet-sized Fortress.{{Fn|1i}}

The Tau were at a slight advantage after Mu'gulath Bay and Voltoris, for the Imperium had transferred much of Prefectia's garrison to wage these campaigns. Surprisingly, Imperial officials were in many ways glad at the Tau decision to not steer further towards [[Dovaris]], and settled in for a new round of fighting.{{Fn|1a}}

A final great clash in this hunt erupted on the ash-strewn wilderness of Prefectia, with Solaq finally cornering Aun'Do. Just as the last of the [[Ethereal Guard]] fell, the Ethereal managed to activate a force shield to protect himself long enough to be air-lifted to safety by Orca. Solaq was seething with fury.{{Fn|1a}}

At the complex, the Scars fell into another trap when Shadowsun collapsed her own Tidewall defenses onto Kor'sarro and his [[Terminator]]s using [[Stealthsuit Team]]s. They then came under attack from a [[Riptide]], forcing the Scars to call in air support and driving the Tau away.{{Fn|1b}}

Meanwhile, Kor'sarro Khan continued his hunt for Shadowsun, who appeared to be commanding from every frontline simultaneously. Shadowsun used her primary lieutenants, [[Commander Swiftflame]] and [[Commander Sternshield]], to bait the Imperials at every turn and cause misdirection as to the Tau's true intent. After Sternshield managed to ride his [[Coldstar]] [[Battlesuit]] into orbit and attach a scanner to the Imperial Navy ship ''Duty's Cull'', the Tau were able to intercept Imperial communications.{{Fn|1e}}

Amid these difficulties, it became apparent to the Tau that Prefectia would not fall in a lightning-fast blitz as they had hoped. An embarrassment for Shadowsun took place when [[Aun'va]] himself appeared on the front to inspire his troops, while Raven Guard [[Chapter Master]] [[Corvin Severax]] arrived to personally finish the fight. Shadowsun's stare was on the wane, the war was becoming prolonged and she was constantly on the move to escape her White Scars and Raven Guard pursuers.{{Fn|1f}}

[[Image:ImpvsTauArt2.jpg|thumb|right|350px|The White Scars and Knights battle the Tau]]

Meanwhile, Shadow Captain Shrike was determined to exact vengeance on Shadowsun for Severax's death. In their hunt for Shadowsun Shrike and his squads were eventually able to destroy several Ghostkeel's by using their own fire against them, as their defensive countermeasures did not register friendly weapons. Shadowsun was unable to be caught, but Shrike was able to make it to the site of Severax's death and secure the [[Gene-seed]] of the fallen. For this, he was elected by the Company Captains as the new Chapter Master of the Raven Guard.{{Fn|1g}}

Shrike set to work on solidifying the alliance between the remaining Raven Guard and White Scars forces on the planet. The two Chapter's played off each others strengths to score several stinging defeats on Tau Cadres from [[Vior'la]] and [[T'au]]. Shrike used the electrodam of Brutec Nexus to unleash a storm of energy across Prefectia's fissure plains, revealing and destroying many Cadres in waves of geometric instability. The Tau quickly struck at the dam complex in the tens of thousands, running into another storm created by White Scars Stormseers. House Terryn Knight's landed directly into the fray via bulk lander, and a vicious duel between Knight and [[Riptide]] teams erupted. The Riptides took heavy losses, and flanking attempts by [[Hammerhead]]s, [[Broadside Battlesuit]]s, and Sniper [[Drone]]s were blocked by Space Marines. Only the arrival of Tau [[KV128 Stormsurge]] Battlesuits were able to prevent a Tau collapse in what would be called the Battle of Goliath's Eye. Nonetheless even these mighty suits took losses, most infamously at the hands of electricity-wielding Stormseers. However the Tau were able to focus their [[Ballistic Suit]] fire upon the Knights, slowly turning the tide and House Terryn was forced to retreat back into their bulk landers. The Raven Guard and White Scars withdrew shortly after.{{Fn|1h}}

Soon enough a surge of Tau reinforcements were able to land, bringing Stormsurge's to every major front on Prefectia. The suits were instrumental in blasting apart Imperial defenses and Hives, allowing for the Tau holdings on the planet to increase. With too many of their assets lost, the Astartes could not contest the Tau advances. Day by day the last Imperial strongholds fell, and the Ethereals declared Prefectia won. It was renamed '''Vas'talos''' in a grand celebration ceremony. Across the Tau Empire, propaganda portrayed this victory as their greatest yet. Shadowsun's image was boosted to the public and [[Ethereal Council]] alike, and she became a hero to the Tau. Tau propaganda broadcasts were kept on a loop for days afterwards as the [[Water Caste]] attempted to maximize the media value of the Prefectia victory. However to the [[Adeptus Terra]], Prefectia had been of little strategic value and it was considered a minor loss on a minor front. The Imperials instead focused on [[Second Agrellan Campaign|reclaiming]] [[Agrellan]].{{Fn|1h}}

Meanwhile, news of the "Great Victory" reached the [[Farsight Enclaves]], and a legendary leader gathered his people for a war that would change the history of the Tau forever.{{Fn|1h}}

*[[Adeptus Astartes]]

**[[White Scars]] — Elements of the [[1st Company (White Scars)|1st]], [[3rd Company (White Scars)|3rd]], and [[10th Company (White Scars)|10th]] [[Space Marine Company|Companies]].

*[[Imperial Guard]]

*[[House Terryn]] [[Knight]]s

*[[Fire Caste]] Commune

**[[Stealthsuit Team]] dropstrike Contingents

**[[Pathfinder]] Recon Contingents

**[[Hunter Cadre]] Contingents

**Forward Stealth Contingents

**Fire Support Contingents

**Dogma Disproval Group

*1: [[War Zone Damocles: Kauyon]]

**{{Endn|1a}}: pgs. 6–12