The Damocles Gulf Crusade: When the Imperium Met the Tau Empire

For most of its history, the Imperium’s answer to an alien empire has been simple: find it, and purge it. In 742.M41 it tried that answer on a young civilisation in the Eastern Fringe, and for the first time in a long while the answer did not work. A crusade of a dozen capital ships, Space Marines from a dozen Chapters and nineteen regiments of the Imperial Guard crossed the Damocles Gulf to destroy the Tau. It ended with Imperial and Tau officers meeting under flags of truce. Reader, this is the chronicle of how the Imperium met the Tau Empire, and why the first great war between them stopped.

A Crusade Typical of the Eastern Fringe

The Damocles Crusade, the Imperial account begins, was a military action typical of the Eastern Fringe before the arrival of the Tyranid hive fleets: wherever a challenge to the Imperium was found, war followed. In 742.M41, a string of Imperial sub-sectors between the Damocles Gulf and the Perdus Rift anomaly had been badly disrupted by Eldar pirate raids and warp storms. As the Imperium tried to restore its grip, it discovered that an alien race called the Tau was allying itself with dissident Imperial factions.

Alien goods and artefacts were turning up in nearby systems, and Inquisitorial investigation found Tau activity in neighbouring sectors. The conclusion was that the Tau represented a major threat. Cardinal Esau Gurney of Brimlock officially called for a crusade to purge them.

The Crusade Musters

The crusade was built around a dozen capital ships, five provisional companies of Space Marines drawn from a dozen Chapters, and nineteen regiments of Imperial Guard, seven of them from Brimlock. Its first target was not an alien world but a human one. In the Timbra sub-sector, human colonists had lived alongside the Tau, and the crusade began by reasserting Imperial rule over the colonies of Garrus and Kleist. Those implicated in dealing with the Tau were seized and punished at a special assize held before the furious crusaders.

Andy Hoare’s Rogue Star novels, which follow a Rogue Trader dynasty attached to the crusade, show how that looked to an outsider: Cardinal Gurney holding the crusade’s reins by influence rather than title, his ally Inquisitor Grand of the Ordo Xenos in the shadows, and hundreds of liberated colonists put to death for welcoming the departed aliens. The Archive notes that these are novel scenes; the codex records only that the guilty were punished.

First Contact at Hydass

The crusade first met the Tau in battle in the uninhabited Hydass system. Seven Tau warships of roughly cruiser size were detected at the system’s edge, and the crusade fleet attacked at once. It discovered that Tau ships could launch powerful torpedo salvoes at long range, breaking up the Imperial formation, and that their escorts could counter Imperial bomber waves. A Space Marine strike cruiser and a squadron of Sword-class frigates made the decisive attack, getting inside the Tau formation and discovering that Tau ships lacked broadside firepower. The Tau launched more escorts to screen their withdrawal; one ship that could not escape exploded as its crew were abandoning it. The Imperium had learned its first lessons about Tau warships, and the Tau had learned theirs about Imperial ones.

Sy’l’kell and Viss’el

The first ground war came on Sy’l’kell, a fertile agri-world with an estimated seven million Tau. Captain Rumann of the Iron Hands took command of the assault, and his warriors boarded and cleansed the orbital station, which became Imperial headquarters. Then the Tau response arrived: a superbly equipped mechanised force with armoured support. The Tau grav-tank the Imperials called the Hammerhead proved a close match for the Leman Russ, and Tau infantry in heavy jump armour ambushed the 17th Brimlock Dragoons in rolling ground. Only the 4th Stormtrooper Company and the Scythes of the Emperor averted a massacre.

As the crusade advanced, the Tau evacuated their most qualified workers and dismantled their advanced technology. When the 9th Brimlock Fusiliers landed, resistance crumbled, and the planet was, in the codex’s phrase, duly cleansed. Meanwhile an expeditionary force dealt with the Tau fishery colonies on the ice-covered sixth planet of the Viss’el system. Seeing no strategic benefit in holding it, the Imperium bombarded it from orbit, melting the ice around the colonies and destroying them.

Pra’yen: A Pyrrhic Victory

After a five-month crossing of the Gulf, the crusade reached the Dal’yth system. The fleet approached the orbital station guarding the outer planet, Pra’yen, too casually. It mounted heavy railguns whose first volley crippled the Honour of Damlass, and as the fleet broke formation, eleven Tau ships emerged from behind the planet. The light cruiser Regent Lakshimbai fought superbly until a lucky shot triggered a plasma drive overload that destroyed her with all hands.

Then came the trap’s last piece: a Kroot warsphere, powering up from nowhere and steering straight for the Imperial transports. Salvation came from Admiral Jallaque’s flagship, the Retribution-class battleship Blade of Woe, which turned across the warsphere’s path and systematically tore it apart. The Tau fleet, station and warsphere were destroyed, but at the cost of four capital ships and fourteen escorts. It was, the codex says, a truly pyrrhic victory, and it brought the Imperial fleet a new respect for the Tau.

Stalemate at Dal’yth Prime

Some commanders argued for turning back, but the lure of a major Tau world was too great. The crusade landed on Dal’yth Prime’s largest continent and advanced along an excellent road network towards the city of Gel’bryn, Titans and armour at the spearhead. Then missiles fired from beyond hills and woods began to inflict heavy losses, and units sent to drive off Tau spotters were ambushed by Tau jump troops with cloaking fields. The attack broke into three spearheads: Titans of the Legio Thanataris, met by Tau Manta missile destroyers; the veteran Rakarshan Rifles, met by Kroot warriors on the rooftops of Gel’bryn; and Space Marines of the Iron Hands, Ultramarines and Scythes of the Emperor, met by the Tau’s heavy jump troops. The front stabilised on a river about twenty miles north of the city.

One Imperial account remembers the Tau commander on the other side. During what it calls the Dal’yth Counter Attack, it says, the Tau, led by the celebrated Commander Puretide, were forced to pull back many ground troops under pressure from the crusade; Puretide had other cadres send their Devilfish transports to pick up stranded Fire Warriors, who then struck within a hundred metres of the Imperial command centre.

Debating the Enemy

The crusade’s divisions over the Tau ran deeper than tactics. In Hoare’s Star of Damocles, the crusade council votes on whether to seek out Tau prisoners for interrogation. The crusade’s Praefect Maximus abstains with a speech that captures the dilemma exactly: to question the Tau would be to open a line of communication, tantamount to recognising their empire and its right to exist, yet to exterminate them outright would throw away whatever use they might be. The purpose of the crusade, he insists, is to challenge the Tau, not to talk to them.

That question, talk or purge, would decide how the war ended. The codex records a growing gap between the army that had fought the Tau face to face and the officials who wished to erase them.

Operation Hydra and the Truce

Commanding on the ground, General Wendall Gauge watched his army bleed. The Tau fought at night, at extreme range, and withdrew at dawn; the battered fleet could barely protect its transports; more Tau arrived every day; promised reinforcements never came. Inquisitor Grand wanted evacuation followed by Exterminatus, but the army had found the Tau to be honourable adversaries and opposed so extreme a sanction. While the council of war argued, Gauge acted. His Operation Hydra forced the river line and came within five miles of trapping tens of thousands of Tau against the sea. Overnight, the Tau slipped away.

Gauge seized the starport and his chance to evacuate. Objections from the Inquisition and the Space Marines were overruled by an express order from Inquisitor Kryptman to return to Brimlock with all available forces. The Tau, the codex says, sensibly realised that getting in the way would serve no sane purpose, and parleys held under flags of truce were honoured by both sides. Why Kryptman sent that order, the codex does not say.

Kryptman’s Message

Hoare’s third novel, Savage Scars, imagines that order arriving. An envoy of Lord Inquisitor Kryptman reaches the council, and then Kryptman himself appears by projection, invoking the authority of the High Lords: every command receiving the message is to cease all military operations and set course for the Macragge system, home of the Ultramarines, mustering every possible asset. His envoy describes a xenos abomination discovered at an Explorator base, able to strip an entire world of its biomass in days, which had already descended on Thandros and then Prandium. After Prandium, the admiral realises, comes Macragge.

The codex and the novel differ on the destination, Brimlock in one and Macragge in the other, and the Archive gives both. What they share is the shape of the ending. The crusade did not lose to the Tau; it was called away by something worse. The Tau remembered it too. In Phil Kelly’s Farsight: Crisis of Faith, a Tau briefing on one Imperial-held world notes that since ‘the Imperial counter-offensive they call the Damocles Crusade’, the humans have reinforced their strength there a hundred times over.

The first seeds of cooperation were sown at Dal’yth, the codex concludes, though they would take time to bloom after so brutal a war. The Imperium had learned to respect the Tau’s skill at war, and the Tau had discovered the true scale and bitterness of a galaxy they had once thought theirs for the taking. A crusade sent to purge an alien empire ended instead by introducing two civilisations to each other. Neither has forgotten the lesson.

Questions from the Archive

What was the Damocles Gulf Crusade?

The Damocles Gulf Crusade was an Imperial military campaign launched in 742.M41 against the young Tau Empire, after Inquisitorial investigation found the Tau allying with dissident Imperial factions in the Lithesh Sector. Called by Cardinal Esau Gurney of Brimlock, it crossed the Damocles Gulf and assaulted the Tau world of Dal’yth Prime before withdrawing under truce.

Who won the Damocles Gulf Crusade?

Neither side decisively. The crusade cleared several Tau-held worlds and won a costly fleet battle at Pra’yen, but it stalled before the city of Gel’bryn on Dal’yth Prime. It then evacuated after an express order from Inquisitor Kryptman. The codex says the Imperium learned to respect Tau skill at war, while the Tau learned the true scale and bitterness of the galaxy.

Why did the Damocles Gulf Crusade end?

The codex says General Wendall Gauge took a chance to evacuate, and objections from the Inquisition and the Space Marines were overruled by an express order from Inquisitor Kryptman to return to Brimlock with all available forces. In Andy Hoare’s Rogue Star novels, Kryptman’s order is tied to a ravenous new xenos threat sweeping towards Macragge.

What happened at Dal’yth Prime?

The crusade landed on the eastern seaboard of Dal’yth Prime and advanced on the Tau city of Gel’bryn. Tau missiles, cloaked jump troops, Kroot and Manta-launched forces broke its spearheads apart, and the front stalled on a river north of the city. General Gauge’s Operation Hydra nearly trapped tens of thousands of Tau, but they withdrew overnight.

Was Commander Puretide in the Damocles Gulf Crusade?

Yes. One Imperial account records that, under pressure from the crusade’s ground forces, the Tau led by the celebrated Commander Puretide pulled back many ground troops during the Dal’yth Counter Attack, using Devilfish transports from other cadres to rescue stranded Fire Warriors and strike close to the Imperial command centre.