1701: The Void Rebellion

During one of the Holy Foundation's campaigns against its enemies, specifically against the recent Anti-Calus Rebels in the Icons of Fuxi, a Tenno designated as VA-6-81 mutinied. They had fled with a few civilians, who they had told their history to, including Foundation Secrets. It had taken a few days to track them, to which Division 95 agents put down both VA-6-81 and the Civilians.
The news of this event made its way to the rest of the Tenno, which immediately caused a great uproar. A third of the Tenno were staunch Loyalists to the Foundation's mission, while the other two thirds had grown disillusioned; and this was the final straw for them. A few hundred over the next few tendays fled Foundation authority, while a Third of all Tenno mutinied, joining the Fuxites and instigating a second rebellion in Tridecagrama.
This quick strike led to an immense explosion of Blue Void energy come from the office of the High Prince in the Ceadda Tower. Investigating officers found the room half blown out, with the floor and ceiling ripped out, and the floors above and below also damaged. the remains of multiple Tenno were found strewn about, but also the mangled corpse of High Prince Calus. His second son and Heir presumptive after the barring of Ragvir from succession, took over emergency powers, arranging an immediate peace talk with the Tenno. They would be allowed free passage out of Tridecagrama, and be given a month until the Foundation would continue any offensive action against the Tenno that joined the Fuxites. The ones that went their own way would be left alone, but observed. This was seen as agreeable, and Tridecagrama was spared yet more violence.
High Prince Perredor would turn the Foundation inwards, rebuilding and holding its own against the Fuxites, while banning any future Tenno production. He also established the High Court Senate again after Calus abolished it, and re-permitted the worship of Saint Gildrich.