Battle of the Startide Nexus
The battle began mere months after the commencement of the Fifth Sphere of Expansion when a sizable Death Guard armada invaded the T'au Empire's newly colonised area of space, known as the Nem'yar Atoll. The Chaos Space Marines launched boarding craft attacks on the Orbital Stations guarding the entrance to the Startide Nexus, which is located within the Atoll and serves as a stable dimensional pathway between the Atoll and the T'au Empire proper. The shocked Tau responded with remarkable speed, destroying many vessels but were overwhelmed by the sheer numbers. The Death Guard were able to board the stations, and a vicious melee battle erupted. Many thousands of T'au lost their lives in the desperate defence of the Nexus.
When Commander Shadowsun learned of the assault she immediately responded, and upon arrival broke down her fleet into small battle groups, each with dedicated targets and responsibilities. Some relieved the defence stations while others engaged Death Guard fleets. Others engaged in baiting attacks and feigned retreats before striking again. Despite these tactics, however, the Death Guard advance could still not be halted. Death Guard vessels advanced on the Nexus and Shadowsun considered that victory might not be possible. She became determined to warn the T'au Empire of the coming threat and sent a drone into the Nexus.
By this point, Shadowsun had begun to become suspicious of the Fourth Sphere of Expansion forces under Commander Surestrike. Determined to learn the truth of what befell the Sphere and the supposed entity they encountered in the Warp. For these actions she was briefly relieved of command by the Ethereal Aun'la and replaced with Commander Surestrike.[4a] However Shadowsun gathered a small group of Tau Auxiliaries which included a Kroot, Nicassar, and Charpactin and boarded the Death Guard Battleship Nephylum. During the subsequent battle Shadowsun was sucked into the void of space but seemingly saved by the same Tau Warp entity that had saved the 4th Sphere. Afterwards, she began to become less distrustful of the emerging cult of the "Goddess T'au'va" and was reestablished by Aun'la as Supreme Commander.[4b]
After Shadowsun's attack, the acting Death Guard commander Oratius Glurtosk was forced to withdraw, but his flagship Nephylum was destroyed in the Warp by the T'au Warp Entity.[4c] Soon the Death Guard vessels began to withdraw from the Nem'yar Atoll entirely. Even more perplexing was that the Death Guard never emerged on the other side to the waiting T'au defence fleets. For months the T'au stood at high readiness, waiting for a foe that never appeared. The T'au are busy analysing what exactly the Death Guard objective in the battle was.
The Battle proved costly to the T'au Fifth Sphere of Expansion, whose fleet was mauled by the campaign. This has blunted the momentum of the Fifth Sphere, and thus a Sixth Sphere of Expansion is being planned.
- 1: Codex: T'au Empire (8th Edition), pg. 39 — March of Conquest: Battle of the Startide Nexus
- 2: Psychic Awakening: The Greater Good, pgs. 4-5
- 3: Codex: T'au Empire (9th Edition), pgs. 26-27
- 4: Shadowsun: The Patient Hunter (Novel):