|United Federation of Planets||Galactic Republic|
Outside of Tranquility Base, Port Luna's greatest claim to fame is that it was the site of the November 2009 Tomed Incident, the bar-brawl-turned-riot that still stands as the largest and most violent interfactional dispute in Fenspace's history.
The Trekkies and the Warsies were the belligerents in this not-quite-war. It took a diplomatic note from both Starfleet Command and the 501st Legion to the people involved – the Treaty of Algeron - to get things under control.
The Tomed Incident encouraged a number of Fen, including a large number of Fivers, to act as unofficial peacemakers between factions. This, and the example of the Tomed Incident itself, made answering the question of "ownership" of Ganymede a far more peaceful process than anyone expected.