Recent advances in Gradient drive technology have made it possible to create a traversable gradient - 'pull a piste' in common vernacular - into increasing numbers of systems, including supermassive stars and binary systems. And all six civilisations have been conducting renewed search and survey efforts within, and beyond, their borders.
Two Short Plancks, an exploration vessel of the Co-Operative, ran across an anomaly nestled in a previously-unexplored region in the vague, messy borders between the civilisations. Observation of gravitational lensing and previous difficulties establishing a gradient into the system had led most people to believe that the star in question was some kind of semicollapsed supermassive body, but what the TSP found was a rather ordinary system, with just one distinguishing feature: a sweet-spot planet, complete with atmosphere and biosphere - and vast deposits of ardanium.
The day co-ordinator handed control of the mission to the most experienced geologist on board, who immediately asked three other crewmembers to launch courier pods back to the main body of Co-Operative space to spread word of the find.
One of the couriers was intercepted, captured, and interrogated several systems away by a Fleet Picket Asset screening for the Interstellar Issue Resolution Asset Optimiser, owned by the Washiru Corporation in the Federation. Their transmissions were intercepted by a Many observation craft disguised as a defunct adult entertainment broadcast satellite.
The Many took steps to inform the Empire, the Distributed Process and the Zebulon, for reasons best known to themselves. And so, fleets from all the Civilisations descended on the planet (named, in the interim, Reddeluto).
As dozens of Imperial and Federal ships squared off against one another, completely ignoring the tiny craft already in orbit and the ramshackle squadron forming protectively around it, a number of the Distributed Process' outlandish vessels entered the system and broadcast a proposal that the riches available on Reddeluto be made available to everyone with the capacity to exploit them. The Co-Operative crews voiced their assent almost as one, but the Federation and Imperial commanders reacted derisively, demanding to know how the NOIs intended to enforce such an idea.
It was at this point that a vast fleet of Zebulon Applied War Studies craft emerged from the shadow of the system's outer gas giant, politely explaining that they would be happy to enforce it on behalf of the Distributed Process, if any of the Human vessels would care to fire the first shot.
When the Many fleet arrived, and immediately threw their weight behind the idea as well, the Imperial and Federation forces were faced with the prospect that the alternative to backing off was not only to take on all the other fleets, but - in order to stand any chance at all - aligning with each other to do it. And thus it was that peace broke out.