The The Coalition of a thousand Free Worlds was declared in the 2830s, to combat supposed injustices and repression in the STUN, and the dominance of the core regions of human space. Within the two decades leading up to the war, it gather power in the outer regions of human space, and became more of a cause to rally behind than any official faction. Eventually, as intermittent skirmishes between STUN- and Coalition-aligned nations and factions increased, the war became officially recognised as such; the Fifth World War, which would eventually come to be the largest war ever fought in human history.
Where and when exactly the war began properly is impossible to determine, but the Odessines, a star cluster about 120 light-years from Earth, were the first large-scale conflict of the war. It alone killed nearly a billion people, and allowed the Coalition a foothold toward the Core Worlds
. The first half-decade or so of the war saw many small advances towards the Core.
The Broad Picture
The main course of the war was a rough yet steady advance of the Coalition towards the Core Worlds. Coalition forces had the initiative in the first decade or so, and could raise larger forces quicker, largely due to them being composed of already existing forces, mostly defensive fleets and the like. However, the ASTUN had the advantage of both more population and more concentrated industry, which allowed them to eventually raise forces that dwarfed the Coalition's, and move them around easier around a smaller front. The technology of the Core is also a significant advantage. The Coalition may have had a larger combined fleet and army, but by the end parts of the war, the ASTUN took that place with its faster recovery rate due to the larger industry.
There were countless battles and small wars throughout the Fifth World War, most forgotten. Even still, for every minor skirmish, there's a Waterloo or Verdun.
The Odessines were the first major site of conflict. The Coalition smashed through the STUN nations' simple defenses, and took the cluster quickly and efficiently, opening a way toward the Core. The ASTUN would eventually retake the cluster, though with great collateral damage.
This star system played host to a particularly destructive battle, involving the ASTUN 1st Fleet, lead by Johan Carte
. Strangely, the system was a barely inhabited one, with the only real settlements being in the asteroid belt, numbering at barely more than 20 000 people, not even enough to count as a major settlement. Even still, Both the ASTUN's first and seventeenth fleets were present here, facing even larger Coalition fleets. The resounding success in the face of such odds ended up as another mark of glory on Admiral Carte's name.
As comparably irrelevant as it is, Ak'Thakra
is nevertheless vital in the region it is in. The cluster is centered around the planet, serving as its only source of antimatter and core of industry and trade. As such, the local Coalition forces are dependent on it. And so, a local ASTUN fleet operating far behind the front line decided to strike a crippling blow, leading to the Battle of Ak'Tharka
, which itself concluded in the near-destruction of the planet's population, and certainly its relevance. It also deprived the local Coalition forces of valuable antimatter, leaving the larger ships crippled.
Ex-Cellean border states
Surprisingly, the old reaches of the Cellean autocratic space
were a not-insignificant part of the war. Most of the fighting war done by local forces independent of both the Coalition or the STUN, and were fighting their own wars, generally. But these wars affected local operations of the two major powers, and so were included in the war. More than a few excursions were made to seize the superior technology of the powers, and some were succesfull, potentially leading to a future shift in power in the region.
The Battle of Earth
was likely the major turning point of the war, marking a shift from the ASTUN being gradually pushed to the Core to a rapid return and bounceback. As the largest individual war in human history, almost a war in itself, it caused the Coalition assault to grind to a halt, allowing the ASTUN to gather its fleets once again.
The war appears to be shifting to the STUN's favour, due to better industry and a more cohesive leadership, as opposed to the lack of any real structure in the Coalition. Still, more and more previously independent nations and factions are joining the Coalition's cause, though some are aligning themselves with the STUN instead. Time will tell what exactly the outcome will be, but what is certain is that human space will be impacted for a long while, for better or worse.