He is mainly known for assassinating General Nikolai Mezentsov, the chief of Russia's Gendarme corps and the head of the country's secret police,[1] with a dagger in the streets of St. Petersburg in 1878.

[1] He received a liberal education, and when he left school, he went on to attend the Military academy and graduated from the Mikhailovsky Artillery Institute before joining the Imperial Russian Army.

He joined the Circle of Tchaikovsky, a group of like-minded Narodnik philosophers and political activists whose ultimate goal was the "liberation of the people.

"[3] Stepniak became a member of the original St. Petersburg branch of the Circle, where he joined thirty other men and women of education, including Pyotr Kropotkin.

To this end, he participated in a precursor to the Going to the People, when members of the Narodnik movement disguised themselves as peasants and laborers to spread the idea of revolution.

[6] He returned to Russia in 1878, joining Zemlya i volya (Land and Liberty), where he along with Nikolai Morozov and Olga Liubatovich edited the party journal.

4 August] 1878, he assassinated General Nikolai Mezentsov,[7] the chief of the Gendarme corps and head of the country's secret police,[1] with a dagger in the streets of St Petersburg.

[9] In England he established the Society of Friends of Russian Freedom and the Russia Free Press, linking with Karl Pearson, Wilfrid Voynich and Charlotte Wilson.

The British socialist and Fabian Annie Besant reviewed Stepniak’s The Russian Storm-Cloud in her journal Our Corner in July 1886.

[9] Stepniak constantly wrote and lectured, both in Great Britain and the United States, in support of his views, and his energy, added to the interest of his personality, won him many friends.

He was chiefly identified with the Socialists in England and the Social Democratic parties on the Continent; but he was regarded by people of all opinions as an agitator whose motives had always been pure and disinterested.

At the Waterloo station, from where the train leaves for Wauking [sic], thousands of workingmen assembled with their banners, representing the societies and Labor Unions of various parts of London.

Opposite the station, in a downpour of rain, speeches were held by English, Russian, Italian, German and Armenian friends, who were often interrupted by the loud sobs of the assembled.