Sinestro and his minions are able to ambush even more Lanterns across the universe and murder even more citizens on any number of worlds, leading the Guardians of the Universe to take drastic measures to combat his overwhelming forces. Hal Jordan - along with Green Lanterns John Stewart and Guy Gardner - takes the fight to Sinestro, but he's unsuccessful. Forcibly ripping the willpower entity known as Ion from Kyle’s body, Sinestro exploits Kyle’s fear, thus allowing Parallax to wriggle its way into Kyle’s mind, corrupting him just like Hal before him and giving Sinestro yet another trick up his sleeve in his war against his enemy. By freeing the recently captured Superboy-Prime and Cyborg Superman from their cells on Oa and recruiting them to his cause, Sinestro inflicts heavy casualties on the Green Lantern Corps and manages to capture Green Lantern Kyle Rayner in the process. Traversing back into the positive universe, Sinestro and his grand army of fear assault Oa with extreme prejudice. With his entire army able to draw on an energy source that exploits the Green Lanterns' major weakness, Sinestro's war begins, and with it one of the darkest times in Green Lantern lore. Having used Parallax in the past to corrupt Green Lantern Hal Jordan, Sinestro becomes somewhat chummy with the fear entity, and exploits the “yellow impurity” chink in the Green Lantern Corps’ otherwise shining armor that limits their ability to fight yellow light if they have not confronted and conquered their fears.
Almost entirely comprised of various villains, evil masterminds, and sadistic criminals, such as the deadly sentient virus known as Despotellis, the baby-snatching monstrosity known as Kryb, and the centuries-old sniper Bedovian, the Sinestro Corps also had another pivotal member: Parallax, the embodiment of fear itself. While the yellow power of fear was once a weapon that Sinestro wielded alone, his army harnessed the energy to create "constructs" of terror, violence and unimaginable dread to take down their foes in the most brutal of fashions.