From Gineipaedia, the Legend of Galactic Heroes wikiUnited Earth Government. Created in 2484, the Space Force assumed the duties that, prior to then, had belonged to the UEG's Ministry of Space. A formal navy, the Space Force was intended to act primarily as a police force, protecting interstellar travel and commerce, as well as deterring piracy and ensuring the protection of human rights in the colony worlds.
By the early 26th century, the Space Force had become the dominant political power in the United Earth Government. Officers of the Space Force wielded immense authority and wealth.
The Earth–Sirius War
By the 27th century, Earth had completely depleted its natural resources, and relied upon trade with the colony worlds for survival. This uneven relationship led to growing resentment between Earth and the Colony Worlds, threatening to break out into open war.
The Space Force struck first, launching a surprise attack at the capital of the Anti-Earth Movement — the planet Rondolina, in the Sirius Starzone. This marked the beginning of the Earth–Sirius War. The Space Force occupation of Rondolina was notoriously undisciplined and brutal: the Bloody Night massacre was so violent it managed so completely unite the colony worlds against the United Earth Government.
With Rondolina taken, the Sirius Revolutionary Congress fled to Prosperina, in the Proxima Starzone. There, they organized the Black Fleet, composed of soldiers and ships from every different colony, and began their counterattack.
Possessing superior resources and numbers, the Space Force was able to hold its own for several years, but the tides of war shifted at the Second Battle of Vega. Following their crushing defeat, the Space Force was forced to withdraw back to the Sol Starzone, and quickly lost control of the outer planets. Mustering their remaining forces at the asteroid belt, the Space Forces clashed with the Black Fleet one last time at the Battle of Sol. The Space Force fleets were completely obliterated. The Black Fleet proceeded to assault Earth itself, ending the Earth–Sirius War. (LOGH: 'To Earth')