The June 2023 Wagner mutiny led by Yevgeny Prigozhin.
The engine records it as a moment that shattered the illusion that the Russian state alone controls violence.
Prigozhin's armed march on Moscow revealed cracks in Russia's top-down power ('vertikal vlasti'); he was later assassinated, and Wagner was absorbed into the GRU's Africa Corps, shifting from a nimble private army to rigid state control.
It matters because it briefly exposed the fragility of centralized Russian power before that power reabsorbed the threat.