Yuika Revolution

Overview
At the pinnacle of Yuika dominance over the galaxy, the Federation's subjects turned on them. What followed was many months of bloodied fighting until the capital was taken in a surprise attack including other galactic powers enforcing the rebellion. The Yuika Federation's aristocracy and government collapsed, leaving the largest power void the galaxy had ever seen.

Lead-up
In the year 5,999,998,004 BCE, in order to fund the Yuika's deadspace research, they cut funding that supported the lower class citizens. Instead of dealing with the discomfort diplomatically, the Federation sent in the military police to quell the riots. This lead to a positive feedback loop, whereas more rioting resulted in harsher treatment, which resulted in more rioting.

Fall of Gutah IV
One planet, Gutah IV, in the outer regions apparently had rioters detonate the self-destruct on the administrative tower, or at least triggered it somehow. It was only rumoured from survivors, as all means of communication were lost at that point. By the time word was sent to the capital and rescue ships were dispatched, all that was left of the city was ruins. The military was slaughtered and the administrative tower was in rubble, possibly from its own self destruct, or from outside assault.

This lead to the formation of what was known as the Gutah Militia, the first open rebellion against the central government of the Yuika Federation. In information released after the fall of the Yuika, it was discovered that the independent sovereignty known as the Advainas were funding and supplying them since before the incident.