First Void War

The Great War, also known as the First Void War, was an extradimensional conflict taking place in the Void and the longest conflict in the Void to date. It pits the Unity Pact, led by the Novayan Stellar Commonwealth, against the Gallian Empire-led Continental System, the barbarian states, the Magnolian-led Imperial Coalition, the Shenjitsi-led Greater East Void Co-Prosperity Sphere, and several independent nations that sought to invade the NSC. Though the NSC saw defeats in the early phase of the war, a general mobilization, the use of attrition, guerrila warfare and WMDs, the first usage of eigenweapons/thaumic weapons, heavy military spending, rapid industrialization and technological advancements, and rapid military buildup allowed the Unity Pact and the Blue Stars Coalition to defeat their enemies.
Though the NSC have never seen a war this vast, it has adapted its strategies after beating back the initial onslaught and organized battles and planetary takeovers which allowed the NSC and the Unity Pact to conscript their enemies' peoples and utilize said enemies' resources, industries and manpower to help defeat their enemies further. Star systems the NSC conquered were then colonized to support the NSC war effort. Such colonization of conquered territories and the utilization of manpower, resources and industries proved useful to the NSC so much that its economic transition to a war economy (or according to rumors, total mobilization) allowed it to provide much needed military equipment and the adoption of an extensive conscription policy gave the NSC military recruits to train and equip at the cost of training time. To overcome the problems of recruitment, Novayan women between ages 16 and 20 are to procreate with Novayan men in order to make the birthrates and recruitment rates synonymous. To fuel its economy, taxes were imposed on individual Novayan citizen to pay for the war, and the NSC set up a fiscal policy which saw the exploitation of conquered territories and use of new economic methods: slave labor was used to mine and farm, with those who worked hard were rewarded with food; NSC ground forces plundered for the wealth of the planetary population; NSC-run banks were created to manage local economies; conquered worlds which saw devastation were terraformed to allow the NSC to grow food; food processing facilities and centers were set up to process foodstuffs, with agri-worlds having the most; the integration of other Unity Pact member-states' war economies; uninhabited worlds and moons (minus gas giants) within pre-war NSC space were also terraformed and colonized; the establishment of military occupation authorities called reichskommissariats; and the takeover of shipyards, war factories, assembly yards, and industrial and agricultural sectors.
By the end of the eons-long war, it has seen the Novayan Stellar Commonwealth as the greatest dominant hyperpower in the Void, replacing the barbarian states, Imperial Coalition, and Continental System. It boasts a massive territory it acqured from conquering and annexing the territories of its defeated foes, a mighty military, and a massive economy. However, by the time the Great War ended, the people of the Novayan Stellar Commonwealth were heavily scarred and traumatized by the whole conflict, which saw massive casualties on an extragalactic scale; the actions, especially some of the decisions, the NSC made to fuel its war effort even horrified its government, military, and aristocratic elite which vowed to never again use questionable decisions and policies for good. As a result of the newly-annexed/conquered territories being added to the NSC, the government was reformed from a unitary state to a federal state, which combined a general government (federal or central government) with regional governments.
The horrors of the war and the actions and decisions its government made to win the war and support its war effort led to the NSC's rapprochment with its conquered enemies and attempts to learn the lessons of the war, an act which surprised many, who initially thought the militaristic NSC as a conqueror now saw it as a traumatized and shell-shocked veteran of a war that was too much even to it. Also as a result of the horros of the war and its actions and decisions, the NSC soon adopted a new foreign policy, one where it will perform a five-year development of an underdeveloped or war-torn world; any world under a global  totalitarian leader or government will be invaded by the NSC Armed Forces, which will also help in rebuilding said worlds.