It all started about 10 years ago.
At the time there was a rise in piracy even to the point that Gateway station was attacked and almost destroyed. It was found that an old admiral had decided that the rebellion was a better deal than retirement and started a small pirate group.
A new business network was starting to grow its way into the sector, seeming to make good small investments they grew to the point of being a small power. Just as the group was starting to make a huge impact on the lesser worlds and bringing them along it was found that the group was a front for the rebellion and that a thought to be derelict ship that was brought in to start a station was being repaired under imperial noses.
With the defection of a Nebulon B frigate the Admiral waited until he knew where the ring leaders were and moved. He sent a small fleet to deal with the supposed derelict Capital ship in the Lepskin Void, it was found to have much better defences than thought. After destroying the mothballed cruiser and several of the surrounding support craft (all marauder corvettes) the Nebulon B and an assassin class corvette escaped off to rescue the leadership of the rebel group.
The first fleet went on to tour the more outlier locations and to show the flag strongly. The escaping ships met up with a second fleet that had left at the same time as the first, laying in wait for any rescue attempt it has already destroyed a small freighter that was looking to help out.
After the failed rebellion the sector Moff started to clamp down on any dissent, especially with in the military ranks. The old admiral is still out there, but now acting much more as a pirate than with any true coordination. A shipyard in the area allows for a much larger and more top of the line fleet to have been created.