Tiber Achilus - Against the T'au: Entrenched and well supplied, Tiber Achilus now turned his attentions to what he perceived as the first major threat to Imperial dominion with the sector: the T'au.His scouts had already gathered vast amounts of data on the T'au Empire's presence within the Jericho Reach, and even before the crusade was formed it was believed that they would likely be the most significant and well organised opposition any Imperial force would have to face.These initial intelligence reports, as well as what little the Deathwatch were willing to pass on, seemed to paint a picture of a stable and expanding interstellar power with control over a significant number of both Human and xenos worlds.The crusade's experiences with Spite and the sedition of its population was also a factor and certainly for Achilus sealed in his mind the notion that these aliens were his primary adversary.It may have also been because Achilus considered xenos the most significant of all the Imperium’s foes, more insidious and cunning than the Heretic or rebel and more numerous than the daemon or mortal servant of the Warp.This was a special hatred no doubt seared into his personality after decades of fighting Orks, Khrave, and Aeldari raiders among the Halo Stars and its bordering sectors.Whatever the motivation, the result was the same. The Lord Militant chose to make his first and most direct attacks against the T'au, pushing into the southern regions of the Reach to vanquish what he considered his primary foe.Mustering around Karlack and Spite, Achilus marshalled four battle groups, containing the bulk of his ships of the line and roughly half of his front line regiments, drawn largely from the Calixian levies. In the vanguard of each battle group, Achilus placed his shock troops and several companies from the Chapters of Adeptus Astartes operating in the Reach.Rheelas, Argoth, Kaggeran, and Wrath were the targets of these battle groups. Achilus hoped that with overwhelming numbers and by striking all four worlds simultaneously he would triumph over any T'au defenders or T'au sympathisers present, capturing the worlds and their systems in short order.Largely unknown to the crusaders, however, was that the worlds they aimed to assault existed outside the T'au military cordon, and the Velk'Han Sept Fire Caste had already decided to pull back from the advancing Imperials.In their wake, the T'au left behind stealth teams with the dual purposes of confounding the enemy as well as gathering data on his strength and tactics.The assaults on Rheelas, Argoth, and Kaggeran (which would later become collectively known as the "Quarantined Worlds") were swift and decisive. On the Mining World of Rheelas only minor skirmishes marred what otherwise would have been the triumphant return of the Imperium.Within hours of the fleet darkening Rheelas' sky, Adeptus Astartes had taken the Granite Spire of Rhee and placed the world's governor and his staff under their 'protection'. It was a similar story on Argoth and Kaggeran, a few rebels making feeble stands against regiments of guardsmen and planetary leaders quickly bowing to Imperial rule.This was of course according to the plans of the Water Caste, who in the days before the invasion had cautioned patience in their Human allies and a promise that the T'au would return to take their world into the fold of the empire.As a result, Achilus wasted little time setting up garrisons on all three worlds, but moved the bulk of his troops to more pressing warzones. Achilus' failure to completely pacify the quarantined worlds would come back to haunt the crusade long after the Lord Militant's demise.For the moment, however, Rheelas, Argoth and Kaggeran had been taken. It seemed to the commanders that they have overestimated the strength of the T'au so close to the Well of Night, which in turn led to them blundering into an expertly timed counter-attack on the world of Wrath.Wrath was the furthest of the four objective worlds and the only place where the T'au chose to make a stand, largely to test the capabilities of the crusaders. Using auspex bafflers and echo-sentries scattered along the edges of the system, the T'au Tal'Sha Cadre was able to move its fleet in behind the Imperial assault forces undetected.As the crusaders unloaded their vessels from low orbit the T'au attacked, targeting the vulnerable transport ships and strafing the drops as they fell into orbit. In the opening hours of the attack, thousands of guardsmen and millions of tonnes of materiel were lost before they even touched the ground, vaporised or incinerated in their grav-harnesses and cargo cradles.Only the timely intervention of Strike Cruisers from the Dark Sons Chapter managed to stop it becoming a complete massacre and allowed enough troops to land and overwhelm the T'au defensive positions on the planet's surface.In the face of the Space Marine assault, the T'au Tal'Sha Cadre pulled back toward the Black Reef. The T'au forces disengaged smoothly and abandoned the world in the space of mere solar hours, as their commanders had always intended.This was a kind of warfare that at first baffled the Imperial crusaders, and they could not understand how the T'au could so easily give ground or abandon whole worlds. It was, however, the T'au tactical and strategic flexibility which would make them so dangerous.Veteran commanders quickly learned that T'au retreats were usually only preludes to counterattacks, often made once the Imperium had advanced and over-extended its lines.Many commanders urged Achilus to press the T'au, and argued that if they could so easily snatch worlds from the xenos they should make an assault on the T'au core worlds themselves.In fact at the time the T'au were still reacting to the arrival of the crusade and their forces were scattered across the sector (many committed to holding off Stigmartus attacks from those worlds facing the Hadex Anomaly).Thus a decisive and aggressive thrust through their lines might have been successful and prevented much of the carnage which was to follow. Achilus however was mindful of not overextending supply lines and leaving vulnerable worlds in his wake, and so he gave the order to hold, reorganise, and fortify.While his commanders grumbled, the more hot-headed among them considered the "old man" far too cautious, though they could not deny that so far the crusade had been incredibly successful, and it seemed that there was nothing that could halt its progress.Of course these first years were a time that would later become known by the commanders as the "false dawn," a time when the true extent of the Imperium's enemies were still unknown and the true battle for the Reach had not yet begun.