The Unification Campaigns is a period of galactic history referring to the first 4 centuries following the War in Heaven, or more specifically 0 AWH to 463 AWH (for humans would be from the year of 2658 to 3121). Starting with the defeat of the extra-dimensional invaders later known as the Unbidden and ending with the annexation of the Sophox Garden of Worlds, the campaigns would see through a combination of war and diplomacy the unification of the entire Milky Way Galaxy under the Greater Terran Union.
Following the War in Heaven, the GTU underwent a major change in how it chose to view and interact with the other races of the Galaxy. Lingering xenophobia, a product of the Great Defensive War had over the centuries given way to grudging respect and even admiration at times. During the war, the protectorate nations, in particular the Rixians and Wessari, would perform above and beyond what was expected of them, and the sacrifices of the Talakur and the Florians resulted in Terran citizens coming to entertain the possibility that non-human species could in fact become upstanding citizens of the Union. In 5 AWH (AKA 2663), the National Assembly passed the Protectorate Integration Act, which allowed for the loyal Terran Protectorates to be integrated into the GTU fully. It also set out means by which a foreign nation could become a Terran Protectorate peacefully and eventually also be integrated into the GTU.
Unlike prior expansion against the Compact, Vol and Latians, it was rare for the GTU to expand of its own volition and the growth of the Union in this time period was markedly slower then in the preceding era. The National Council, mindful of the pitfalls of empire and the dangers of expanding beyond the capability of the government to control its new territories adopted a largely passive campaign. It was aided in the fact that following the War in Heaven, Terran ideals and political philosophy gained massive traction throughout the galaxy, with many races adopting a Terran based education curriculum and attempting to reorganize their shattered societies around the principles they learned from them. More often then not, the races of the galaxy would eventually petition for entry into the GTU of their own volition, though others like the Priki-ti-ki would find themselves forcibly integrated due to their involvement in Union police actions or pacification campaigns.