~400 (including Zerg)
After pulling out of the Confederate Marine Corps upon the establishment of the Terran Dominion, Jennifer Geng and several other former marines became mercenaries and formed the all-female Dishonored Shieldmaidens, instead of joining the Dominion military. Through the years, the Dishonored Shieldmaidens earned a reputation for doing exactly as told by their clients.
Zerus II Civil WarEdit
Some time during the Second Great War, Geng was telepathically contacted by brood mother Ma'sram, who's brood had faced the Shieldmaidens before in a previous battle. Knowing of the mercenaries' prowess, Ma'sram requested the Shieldmaidens' assistance to fight against a rival brood mother in order to claim Zerus II. As both Zerg and Terrans value minerals, that would be Ma'sram's payment. The shieldmaidens succeeded in driving away the other zerg and killing the rival brood mother.
Ma'sram asked the Shieldmaidens to stay behind for one more task. This would be the first time for her to test her new Brood Drones: male infested terrans used to breed sexually with female terrans. Geng would be the first to volunteer, giving birth to a larva after mating with a Brood Drone. Geng herself directed the creature's every move, and had it evolve into a hydralisk. The advantage of this method was that the evolution would come at no cost. Soon, other shielmaidens did the same, creating their own expendable army.