As a scion of the Confederacy’s elite Old Families, Mengsk had an easy road ahead of him: inherit his parents’ vast fortune and live a life of fame and power. Yet following in the footsteps of his father, Angus, a Confederate senator on Korhal IV, wasn’t for Arcturus. Even from a young age, he was determined to make his own way in the galaxy.
Much to the chagrin of his parents, Mengsk’s ambitions led him to join the Confederate Marine Corps. There he hoped to learn the finer points of prospecting, a profession that had intrigued him for some time. As tensions between the Confederacy and the Kel-Morian Combine rose, Mengsk found himself embroiled in the brutal Guild Wars. As a Marine, he became known for his brilliant tactics and innate leadership skills, but a life in the military was never his goal. Before the Guild Wars ended, Mengsk left the marines and began his prospecting career on the fringe worlds.
After Mengsk hit pay dirt as a prospector, his world turned upside down. Angus had declared Korhal’s independence from the Confederacy, which responded by assassinating Arcturus’s entire family. Although intended to decapitate Korhal’s budding revolution, the attack had an altogether different effect: it transformed Mengsk into the uprising’s greatest leader. Mengsk had never agreed with his father’s fiery anti-Confederate rhetoric in the past, but his family’s deaths filled him with an unwavering desire for vengeance.
As Mengsk waged a crippling guerilla war against the Confederacy, his enemies responded by bombarding Korhal with one thousand Apocalypse-class nuclear missiles. The attack annihilated all life on the planet. Mengsk, who had been off world at the time, renamed his revolutionaries the Sons of Korhal in honor of those who had died, and he continued his uprising with increasingly ruthless tactics. Around the time when the zerg and the protoss appeared in the Koprulu sector, Mengsk’s forces infiltrated the top-secret Jacobs Installation on Mar Sara and acquired plans for the psi emitter, a Confederate weapon capable of drawing zerg to its location en masse.
The psi emitter was the final nail in the Confederacy’s coffin. Despite the indiscriminate slaughter that using the device would lead to, Mengsk deployed multiple psi emitters on Tarsonis, the capital world of the Confederacy. Zerg soon arrived and overran the planet, dealing a deathblow to the Confederacy in the process. With victory at hand, Mengsk departed Tarsonis and abandoned Sarah Kerrigan, an ex–Confederate ghost and his second-in-command, on the planet’s surface. His disregard for his former ally, however, would carry disastrous consequences. Rather than killing her, the zerg captured Kerrigan and transformed her into the Queen of Blades, a merciless being who would later become the savage aliens’ matriarch.
After the Confederacy’s downfall, Mengsk declared himself emperor of a new government: the Terran Dominion. Yet as his empire began to take shape, the United Earth Directorate arrived in the Koprulu sector and seized control of the recently terraformed Dominion capital planet, Korhal. Due to the circumstances, Mengsk’s only choice was to join forces with Kerrigan and her zerg, as well as with freedom fighter Jim Raynor, an ex–Sons of Korhal member who now leads an anti-Dominion rebel group called Raynor’s Raiders. With his allies’ help, Mengsk recaptured Korhal, only to be betrayed by Kerrigan afterward. Mengsk retaliated against the zerg to disastrous consequences: most of his forces were obliterated, and he retreated to Korhal.
In the four years since, Mengsk has continued rebuilding and expanding the Dominion, ever wary that Kerrigan might strike again. He has also reconnected with his son, Valerian, a child born of a brief relationship with Juliana Pasteur during Mengsk’s days in the Marine Corps. Although he was absent for nearly all of Valerian’s life, Mengsk has recently spent a great deal of time grooming his son to one day inherit the Dominion. To Mengsk’s delight, he sees a bit of himself in Valerian – a man guided by his own will and no one else’s. Mengsk’s oppressive rule and powerful position have also made him the target of various terran revolutionary groups. Chief among them is Raynor’s Raiders, which has been a constant thorn in Mengsk’s side ever since it broke away from the Sons of Korhal. On top of simply trying to exterminate these rebels, Mengsk has also used propaganda to turn public opinion against them and paint their leader, Jim Raynor, as nothing more than a ruthless terrorist.
Mengsk’s sway over the public extends far beyond tarnishing the reputations of his enemies. Through his oratorical mastery and firm control over the media, he has kept his past – and present – atrocities hidden from the public. Most of the Dominion populace accept Mengsk’s rule, believing him to be the only leader capable of protecting them from the alien threats in the Koprulu sector. Mengsk asserts that humanity’s only chance to survive the dark days ahead is to be united under his leadership, whether by choice or by force.