Helghast Colonel Vyktor Kratek was in charge of Diortem's invasion. Kratek chose to hire Phantom Talon Corp to execute ISA admiral, Alex Grey and destroy her cruiser for his ground forces led by Captain Marvidakis to move in the city. Two Phantom mercenaries, Arran Danner and Damian Ivanov accept the contract and were sent to Grey's cruiser just above Diortem. Kratek knew Grey's cruiser would be well defended from the inside, so Kratek chose Commander Soteris and his squad to aid the two Phantom mercenaries. Kratek sends fighters to distracts the ISA's Navy forces while the Phantom mercenaries and Commander Soteris get inside the cruiser.
The mission was successful with Grey killed, and by planting C4 on the cruiser's reactor, the cruiser was destroyed, allowing a ground assault on the already exhausted ISA defenders, who are surrounded and destroyed over a two week course, giving the Helghast another foothold north of the equator.