Xanthus provokes war with Tau

In early 07.011M42 Inquisitor Xanthus once again attempted to break the Tau-Imperial peace agreement and this time he succeeded. Xanthus had previously tried to break the treaty by provoking the Tau, but with little success. His opponent, Hathek, had always managed to box in his forces and smoothe over Tau anger whenever he did manage to land blows on the alien empire.

Xanthus realised that while he was close to Hathek's powerbase in the Perseus Deeps, he would never materially influence the course of events, so he moved in secret to the Mabb Nebula in the Zadoc subsector.

With the help of the Dark Angels and Blood Martyts, Xanthus managed to move a small portion of his forces to New Cerberex, a fiercely puritan Imperial colony. On 0407.011M42 the Dark Angels launched an attack on Hylas, inserting a small force of just a few marines, killing Tau colonists indescriminately and capturing a Tau ethereal.

The Grey Knights, loyal to Hathek and the crusade council, uncovered Xanthus' plan and rushed to New Cerberex to attempt to capture the puritan inquisitor. After being unsuccessfully ambushed by a squad of Blood Martyrs, the Grey Knights then attempted to rescue the Tau diplomat, but the Dark Angels were not above killing their fellow astartes. The Ordo Malleus force was unable to penetrate the Dark Angels' base perimeter, and the Tau captive was tortured and murdered, his head sent back to the Tau as a warning, or statement of intent.

By 1107.011M42 Xanthus' plan had borne fruit. The Tau, unknown to the Inquisitor, had contacted Hathek. The peace treaty in the Perseu Deeps would hold, but such attacks in the Mabb nebula could not be tolerated. Hathek was told in no uncertain terms that since he could not deal with his fellow Inquisitor Lord, the Tau would.

The next Tau move was to deploy a small scouting force to Tyndareous, who were accidentally discovered by a patrol of Blood Martyrs marines who had arrived with Xanthus some weeks before. Xanthus knew the Tau would attack either New Cerberex or Tyndareous, so posted forces of marines on both worlds. The Tau were able to defeat the Blood Martyr's patrol, and before the astartes could get warning to other Imperial forces on the planet they launched a sizeable strike on the planet's main airbase.

The Tau arrived without warning, a tiger shark and several baracuda air superiority fighters screaming in low over the plateau on which the base stood. Taken by surprise the Imperial base was almost defenceless, but a squadron of Prozan Cavalry valyries and vultures still scrambled to intercept their enemy. The battle was utterly one sided. Without taking any damage, the prozan aircraft were smashed from the sky, and the Imperial base was heavily damaged. War with the Tau was well and truly joined.