Nicholas I, alarmed at the prospect of the revolutions of 1848 spreading to Russia, saw great danger in organisations like the Petrashevsky Circle. In 1849, members of the Circle were arrested and imprisoned. A large group of prisoners, Dostoevsky among them, were sent to Semyonov Place for execution. As they stood in the square waiting to be shot, a messenger interrupted the proceedings with notice of a reprieve. As part of a pre-planned intentional deception, the Tsar had prepared a letter to general-adjutant Sumarokov, commuting the death sentences to incarceration. Some of the prisoners were sent to Siberia, others to prisons. Dostoevsky's eight-year sentence was later reduced to four years by Nicholas I.