Sinestro was formerly a member of the Starbrand Corps. When Uatu the Guardian decided to kill every member of the Corps, Sinestro was one of his victims. Unbeknownst to Uatu, Sinestro had survived the murder attempt. Scheming to collect alien rings so he could be powerful enough to get revenge on Uatu and anyone associated with him, became a villain and renamed himself Mandarinestro.
Mandarinestro had a small base on the dark side of the moon, plotting ways to defeat Iron Lantern and gain the power from Oa the Living Planet to become the most powerful being in the universe. To defeat Iron Lantern, he revived Madame Sapphire to kidnap Senator Ferris, who was in Coast City to watch the test-flight of an experimental aircraft.
Mandarinestro later tricked the Green Guardsman into stealing the power-battery from Stark Aircraft, promising him the chance to replace Iron Lantern. Having received the power battery from Green Guardsman, he was about to kill him so he could use the battery for himself. However, Mandarinestro was defeated by Iron Lantern, Madame Sapphire, Green Guardsman, and Tagak the Lantern Lord.