In the second half of the 21st century, a breakthrough in faster than light technology was achieved. A multi-national organization was set up to explore for colonizable planets. Over the next five centuries, hundreds of suitable planets were discovered, although most were separated by considerable distances. Average transit times between Earth and the colonized planets were 3.4 months. The furthest planets were over eight months away. Due to the uneven distribution of suitable planets around the Earth, most of the colony planets were located toward the center of the spiral arm. Not all the colonized planets were equally hospitable. Some were more attractive than others, and their populations grew faster.
By the mid 26th century, there were a dozen worlds with the same level of technology as Earth and populations of half a billion or more. The organization evolved over those five centuries into the Federation of Planetary States. Due to Earth’s higher population, it continued to dominate the FPS Assembly, which passed laws benefiting Earth-based corporations at the expense of the inhabitants of the planets those corporations exploited. The FPS Navy (referred to by colonists as the FEDs) consisted mainly of lightly armed but unarmored patrol cruisers designed mainly for anti-smuggling and anti-piracy duties.
By 2535, several of the more developed planets began secret discussions to form closer economic ties, with the possibility of a more formal political arrangement. A year later, they and six other planets signed a treaty forming a customs union, along with agreements on technology sharing, mutual investment and the establishment of their own shipping company to compete with Earth-based shipping monopolies. Those shipping monopolies pressured the FED Navy to harass the colonial freighters with frequent inspections and citations for technical infractions. Late in 2537, the heads of the signatory planets met secretly and agreed to form the System States Union and secede from the FPS. The new SSU government, headquartered on Sparta, began to organize itself and its armed forces in secret. Sparta’s newly announced Planetary Defense Force (legal under the FPS Constitution) provided the cover for training the core of the SSU Navy. The plan to take over FED Navy and Army assets was set for day 31 of 2539.