The Udug Hul were the elite gene-forged slave soldiers of the Great King of Akkad, who fought the Emperor's forces during the Unification Wars.
Their bodies contained poisoned blood and had strength greater than 10 un-enhanced warriors, which made them the terrors of the Upper Asiatic Basin. This had allowed the Udug Hul to resist the advance of the Emperor's armies, until 668.M30 when He led the first of the Legio Astartes against them and the Great King. Though they numbered 200,000 at that time and faced merely 10,000 of the First Legion, as well as contingents of four other Legions, the Udug Hul were utterly defeated at Samerkend. At the battle's end, the few surviving Udug Hul were left scattered and leaderless, as the Great King of Akkad had been killed as well.
- 1: The Horus Heresy Book Nine - Crusade, pgs. 84-85