From Halopedia, the Halo wiki
Levosia is a human colony world located in the 26 Draconis system. It was founded sometime before the year 2494. This colony was one of the first battlegrounds between the UNSC and the Insurrectionists.
Rise of humanity
In the early 2490s Levosia was suspected of diverting refined selenium and technetium, elements that could be used to make Shaw-Fujikawa Translight Engines, to the black market. UNSC CENTCOM, desperate not to allow insurgent forces access to FTL drives, ordered the UNSC Navy to blockade and search all ships in the 26 Draconis System for contraband. This blockade led directly to the Callisto Incident, which effectively sparked the Insurrection.
List of appearances