Antonov-Ovseenko returned to Russia in June 1917, joining the
Bolsheviks upon his arrival. As a member of the Military Organization under the Central Committee of the RSDLP(b), Antonov-Ovseenko was sent to Helsingfors (
Helsinki) to conduct propaganda work among the soldiers of the Northern Front and the sailors of the Baltic Fleet. He was briefly head of the party organisation in Helsingfors and Chairman of the Northern Congress of Soviets. At the same time, he edited the newspaper
Volna. After the
July Days, he was arrested by the Provisional Government and imprisoned, with Trotsky, in
Kresty prison, where, together with
Fyodor Raskolnikov, on behalf of the arrested Bolsheviks, he drafted a written protest against their arrests. After being released on bail on September 4, 1917, the day that the right wing military revolt led by General
Kornilov collapsed, Antonov-Ovseenko returned to Helsingfors when Tsentrobalt appointed him as a commissioner to the Governor-General of Finland. Antonov-Ovseenko returned to Petrograd in October 1917 following the
October Revolution and was appointed secretary of the Military Revolutionary Committee of the
Petrograd Soviet. Trotsky, who witnessed him in action, described him as "politically shaky, but personally courageous – impulsive and disorderly, but capable of initiative..." John Reed recalled in his book
Ten Days That Shook the World: "In a certain upstairs room sat a thin-faced, long-haired individual, once an officer in the armies of the Tsar, then revolutionist and exile, a certain Avseenko, called Antonov, mathematician and chess-player; he was drawing careful plans for the seizure of the capital." As part of the "operational troika" (together with
Nikolai Podvoisky and Grigoriy Chudnovsky), he prepared the capture of the
Winter Palace. In his report at the meeting of the Petrograd Soviet on October 23, 1917 he reported that the Petrograd garrison as a whole was in favor of transferring power to the Soviets, the Red Guards had occupied arms factories and warehouses and were arming themselves with captured weapons, the outer ring of Petrograd defense had been strengthened, and the ability of the headquarters of the Petrograd Military District and the Provisional Government to respond to the actions of the Bolsheviks had been paralyzed. He personally led the famous
storming of the Winter Palace on 7 November (25 October according to the
Julian Calendar still used in Russia at the time), when
Red Guards broke into the building where ministers of the
Russian Provisional Government (other than
Prime Minister Alexander Kerensky), had taken refuge, and arrested them. They included Kerensky's Minister for Justice,
Pavel Malyantovich, who had given Antonov-Ovseenko sanctuary ten years earlier. There were no lives lost in the incident, which took on something of a mythical status in Soviet history. The Soviet authorities reenacted it three years later in a
mass spectacle involving more than a thousand actors and extras that was viewed by 100,000 spectators. It also provided the climax of the classic 1928 silent movie
October, directed by
Sergei Eisenstein, in which Antonov-Ovseenko took a starring role, playing himself. Antonov-Ovseenko reported to the deputies on the imprisonment of the ministers of the Provisional Government in the Peter and Paul Fortress at the Second All-Russian Congress of Soviets, which was taking place at that time on 26 October 1917. He was appointed to the
Military Committee of Sovnarkom under the Council of People's Commissars at that Congress. ==Participation in the Civil War==