Why Tarsis Major?

How Tarsis Major came to be an unlikely and chaotic four-way struggle is an interesting piece of history. Each of the three invaders had their own powerful and conflicting motives, motives strong enough to ensure that all four of the combatant parties on Tarsis Major became stubborn and unwilling to give ground in the war of 008M42.

The Imperial civilised world of Tarsis Major, with its population of 3.7 billion, is the key to the entire sector. It sits on the only navigable route from Libria and Zadoc to the Hub systems and Terra itself. Throughout the centuries it has been invaded twice, once being totally overrun by Orks, but in the main the planet has grown rich and a little decadent, profiting on rich trading from Terra to the outlying systems.

Since 006M42 its fortunes had declined somewhat, following the loss of the Aleph subsector, but trade between Zadoc, Libria and Terra had for the most part kept the planet content. However in 008M42 it became clear its invasion by at least one of the Imperium’s enemies was imminent, and it began arming for war.

The forces of Chaos were first to consider invading the planet. Gains in the Shadow Worlds and the Rim Worlds had been encouraging, but both the Catechism and the Night Lords wanted more, something grander, and their bases on Typhon and Priam meant the supply distances, prohibitive in previous years, were now short enough to make the invasion possible. In addition, the distance was short enough for the full scale use of the Catechism’s newly completed “Device”.
As it became abundantly clear that Chaos forces were about to invade Tarsis, the Tau considered their options. Tarsis lay on the only navigable route from their holds in the Perseus Deeps and Melberg, to the rich pickings of the Imperium hubward. Further expansion required, at some point, the pacification, conversion or invasion of Tarsis Major, but the Tau had hoped this would be some time away. Many were unwilling to commit to another full scale invasion so soon after Melberg.

The invasion by Chaos changed things. If Tarsis fell to Chaos the planet would become a corrupted fortress, of little material worth but still strategically vital to Tau expansion. Several Water Caste members were dispatched to the system to negotiate an alliance to prevent the Imperial world falling to Chaos, but the Imperial agents saw through their diplomacy and they were all killed out of hand by the Inquisition.

Despite their concerns the Ethereals gave their blessings to a new invasion. If they struck now while the forces of Chaos and the Emperor were fighting each other, they would get a foothold on the planet at the very least, while the system was vulnerable. In addition if their foolish human enemies fought among themselves they would be less able to deal with a Tau invasion. Satisfied that this was the best time to strike, the Tau prepared once again for full scale war.

The Orks were the last to join the party. Warlord Nazghat had no intention of invading Tarsis, hoping the distraction of a three way war would enable his conquests of Zadoc and other nearby worlds to go more smoothly. Unfortunately Orks don’t always think strategically. While Nazghat was blessed with a superior Orky sense of strategy, his sub commanders weren’t and even went so far as to accuse Nazghat of cowardice when he declined to invade Tarsis major.

Many Orks saw the upcoming battle as too good to miss, with Tau, Imperial and Chaos fighting forces in abundance to test themselves against. Reluctantly, realising that to split his forces would be to invite disaster, he agreed to invade the system. It was just as well, as several Ork warbosses had already teleported aboard their ramshackle “invayzhon” barges and disappeared in the general direction of Tarsis…