Colony One was the capital city of Ylesia. It was located on the shore of the oceanic Zoma Gawanga, between Colony Two and Colony Three. The Altar of Promises and the Mountains of the Exalted were nearby. When it was discovered to be the Peace Brigade's headquarters, it was invaded by the New Republic and Twin Suns Squadron. When the New Republic took the city, Senator Pwoe and Thrackan Sal-Solo were arrested.