Green Skin Orcs, of course, had no need to rule over humans. They indeed captured prisoners and enslaved humans, but these were sporadic cases; most of the time, they chose to slaughter. However, the forces that Green Skins deployed on various planets were actually insufficient.
Four years ago, Titus leading the Green Tide, in just a few short months, had spread the flames of war across hundreds of worlds in the Dragonhawk Star Domain. His method was certainly not to conquer each planet one by one; how slow would that be?
In any case, at that time, the human fleet had been defeated by him and was only concerned with fleeing. The vast Star Domain was all exposed, so naturally, he took his fleet and chased them down relentlessly. The many Star Systems they passed through were casually populated with tens of thousands, millions, tens of millions of youngsters and about weather whatever amount depending on the value of the planet.
