The Day 100,000 People Vanished!
When the entire population of Valdale suddenly vanishes, Green Lantern's astral form is summoned by the Guardians of the Universe. The Guardians tell him of Sinestro, an alien they chose to be the Green Lantern of Korugar. However, Sinestro abused his powers and used them to enslave his planet and install himself as dictator.
Sinestro turns to evil as his guide!
As punishment, the Guardians stripped Sinestro of his powers and banished him to Qward in the Antimatter Universe. They then warn that Sinestro has formed an alliance with the Weaponers of Qward to finally defeat the Green Lantern, by potentially exploiting his vulnerability when his power ring's 24 hour charge runs out. Part of the plan was to transport people from Valdale to Qward in a sweeping attempt to capture Green Lantern, who was scheduled to be in that town.
Sinestro evil rant