Heavy Gear Blitz!
When finally Earth returned to its wayward colonies it was not as a friend, but as a conqueror. The New Earth Commonwealth (NEC) government knew the colonies would not welcome them back with open arms after being abandoned for hundreds of years. The Gateships were refurbished and warships were built as quickly as possible, based around modular design elements. The Colonial Expeditionary Force was created with legions of hovertanks, trans-orbital fighters, and their genetically engineered clone super soldiers the GRELs. Then the eight fleets carrying the largest fighting force in human history was sent to bring the colonies back under Earths control.
Terra Nova wasn’t the first stop for these fleets though. Other colonies who had long since lost contact with their homeworld were meant to be quickly subjugated, and whatever forces were competent and trustworthy enough to be integrated into the Colonial Expeditionary Force would be used to bolster their number. As it turned out, the colonies were far from helpless. Even worlds like Eden, whose forces were technologically inferior and fewer in number, still put up a fight. However, it was the conquest of Caprice that was to prove the most costly. In the end, the CEF faced logistics and personnel issues which were only slightly offset by their new auxiliary troops. When the CEF came to Terra Nova, the first wave of troops found organized resistance that was fiercer than any before it… and eventually, they lost.
The CEF’s fleets are still out there making progress toward their overall goal, but Terra Nova is safe from them for the moment. That said, when the CEF retreated from Terra Nova, they left behind a lot of ground troops and equipment; particularly, GREL super soldiers. Their number is such that, on occasion, CEF remnants have risen up to cause problems, but this is a hostile response to the provocation of their only settlement on the planet, Port Arthur.