Tagantsev conspiracy
The Tagantsev conspiracy (or the case of the Petrograd Military Organization) was a supposed monarchist conspiracy, largely fabricated by the Soviet secret police in 1921 to both decimate and terrorize potential Soviet dissidents against the ruling Bolshevik regime. As its result, more than 800 people, mostly from scientific and artistic communities in Petrograd (modern-day Saint Petersburg), were arrested on false terrorism charges, out of which 98 were executed and many were sent to labour camps.