The Battle of Ha'tin was a significant engagement between the forces of
Outremer under
Gui de Lusignan and
Renaud d'Châtillon and T'au forces lead by
Commander Farsight. Taking place during Farsight's attempted reconquest of worlds lost to the Damocles Crusade it was one of the earliest conflicts between Outremer and the T'au and was a significant and destabilizing defeat for the humans which led, ultimately, to the exile of
Baudouin d'Châtillon from Outremer and the schism within the Black Templars leading to the formation of
Les Chevaliers d'Outremer.
The Conflict
Prelude
After the withdrawal of Imperial forces following the end of the Damocles Crusade the T'au began a campaign of reconquest lead by Commander Farsight. Encouraged by the Water Caste to provide immediate and recognizable victories for their propaganda, he concentrated his efforts on planets surrounding the Sept world of Dal'yth, ignoring other territories conquered as part of General Gage's offensive to the galactic west of the crusade's initial beachhead. Conservative elements within the Fire Caste, uncertain of the young commander and supported by the Ethereals, additionally urged Farsight to confine his efforts to territories previously held by the T'au Empire and not attempt to expand into the Damocles Gulf.
As the independent human realm of Outremer lay partially within the Gulf, Farsight knew he would be unable to effectively prosecute a war against it - he would lack support from his superiors in the Fire Caste, the propagandists in the Water Caste, and even the Ethereals, especially if the Outremarin withdrew to or struck from territories within the Gulf. With his agreement Water Caste diplomats met with Baudouin d'Châtillon as a representative of Outremer and brokered a non-aggression pact, which was broadly popular among the Outremarin and even agreed to by Baudouin's brother Renaud.
As Farsight prosecuted his war of reconquest around Dal'yth, however, the temptation to break the pact grew for Renaud. The T'au's rear flanks were lightly guarded and some of the Gue'vesa worlds were resource-rich. Outremarin raiders harried the worlds within the Marches, with Renaud leading one raid that captured the co-ruler of the Gue'vesa settlement of Antak'ya who refused his advances. Her fellow-administrator sent a message to Farsight and begged for his aid. The T'au commander gathered an army and personally led it west.
Reynaud, who to preserve the illusion these raids were the work of pirates and renegades rather than Outremarin forces had not fought aboard his Knight Arnat, fled to the desert world of Ha'tin with his prize. Farsight's forces pursued him and boxed his raiders into the caldera of an extinct volcano. There the humans captured a T'au settlement, taking its inhabitants hostage and using them as xenos shields.
The speed of Farsight's advance had left the Ethereals accompanying his army behind; the collectivist pragmatism of the T'au was blunted and he did not assault. Furthermore his force had traded firepower for speed and so lacked heavier weapons necessary to break the siege swiftly. Farsight scouted the caldera and waited for reinforcements to arrive, while Renaud sent a message to Outremer. Receiving it Gui de Lusignan quickly gathered a force and lead it to Ha'tin.
Renaud's force took refuge in a T'au settlement within the caldera of an extinct volcano, fortifying the buildings. Farsight's force took position on the heights above, using the rim of the caldera as cover. The open ground of the crater made it difficult for the T'au to approach unobserved, although they were able to capture the settlement's water processing plant and disable it, denying water to both the Outremarin and their hostages (but the xenos' physiology was less impacted by such privation compared to the human's). Gui's relief force deployed from orbit into a nearby valley and was able to use the mountainous terrain to shield its advance from the T'au
The caldera of an extinct volcano on the planet of Ha'tin, set within mountainous terrain which blocked line of sight. Ferrous ores in the mountains interfered with the sophisticated sensors the T'au relied on and the humans were able to take advantage of their more primitive scouting methods.
Gui de Lusignan made planetfall with a heavily-armored and mobile force and swiftly moved through the mountains to fall on
Farsight's rear. Utilizing astropathic communication the two elements of the Outremarin forces - Gui's advancing column and Renaud's trapped raiders - were able to coordinate their assault and the raiders staged a breakout at the same time as Gui's troops fell on the rear of the T'au.
Farsight was initially caught off-guard by sudden assault of Imperial heavy armor assets as well the desperate ferocity of the parched raiders trapped in the caldera; Renaud's force was able to close the distance without suffering debilitating casualties and were able to wreak havoc within the T'au ranks in melee combat. Correctly recognizing, however, the poor physical condition of the humans who had been deprived of water and surmizing they would not be able to sustain combat for long, Farsight ordered his troops to disengage from Gui's heavier force and fall back into the caldera.
Initial casualties increased as the T'au and humans were closer pressed and the T'au could not bring their firepower effectively to bear, but Gui's armor assets were unable to target the xenos without hitting allies and could not safely pursue on the treacherous scree of the caldera. T'au battlesuits were able to maneuver with jump jets and soon the tide of battle turned. Most of the raiders were slain with Renaud and others being captured.
Pressing heedlessly forward in his Knight
Sapientia Gui lost his footing in the caldera and was swamped by T'au battlesuits and forced to eject as it lost mobility due to catastrophic knee damage. Recognizing the futility of pressing the offensive any further Gui ordered a withdrawal shortly before he was captured, and the remains of the force disengaged as best it could.
