Tagantsev conspiracy (or the case of Petrograd Military Organization) was a non-existent monarchist conspiracy fabricated by the Soviet secret police in 1921 to terrorize intellectuals who might be in a potential opposition to the Bolshevik regime. More than 800 people, mostly from scientific and artistic communities in Petrograd (Saint Petersburg) were arrested on false terrorism charges, 98 were executed and many were sent to concentration camps. Among the executed was the poet Nikolay Gumilev, co founder of the influential Acmeist movement.