In 361.M37, an army of the renegade Alpha Legion invaded the Mihok system. The three outer worlds quickly fell under the sudden attack, but when the renegade Legionaries reached Mihok Secundus, they found the world already garrisoned by two Cadian regiments (the XV "Kalliagh's Heroes" and the XXII "Bloodhounds of the Emperor"). The XXII was stationed in Cobalt Valley.
Within a thousand miles, the fifty-mile long valley was the only reliable route through the equatorial mountains, and represented the most important strategic location in the defense against the invaders. Along one side of the valley was the Opal Ridge, one of the highest elevations in the mountains and an excellent position for extensive artillery. Within the valley itself was the property of the Vice Governor, and served as a supply and munitions depot, and contained the only free runway in the region. Thus the "Bloodhounds" were commanded to hold the valley at all costs. The Bloodhounds were soon faced by the Alpha Legion which stormed their positions.
After three weeks of continual struggle, Imperial regiments of Cadia, Gorin V and Linnerberg arrived, finding a cratered wasteland and only a few surviving defenders, but the renegade Legion defeated. For their role in the battle the XXII became exempt from active service, transferred to the Explorator Fleet and establishing a new world to settle. Such honour for regiments is normally awarded at the earliest only after ten years on the front.
- White Dwarf 240 (US): Glorious Battles of the Imperial Guard (part 2): The Defense of Cobalt Valley