The group became increasingly radical as World War I progressed and the economic situation worsened, encouraging street demonstrations and issuing revolutionary proclamations.

On January 27, 1917 (all dates Old Style) the entire leadership of the Central Workers' Group was arrested and taken to the Peter and Paul Fortress on the orders of Alexander Protopopov, the Minister of the Interior in Imperial Russia.

The following day, February 28, was the plenary session; elected representatives from factories and the military joined the soviet, and again moderates dominated.

The members of the executive committee, called Ispolkom, came only from political groups, with every socialist party given three seats (agreed March 18).

The Soviet was not opposed to the war – internal divisions produced a public ambivalence–but was deeply worried about counterrevolutionary moves from the military, and was determined to have garrison troops firmly on its side.

The Petrograd Soviet developed into an alternate source of authority to the Provisional Government under (Prince) Georgy Lvov and later Alexander Kerensky.

This created a situation described as dvoevlastie (dual power), in which the Petrograd Soviet competed for legitimacy with the Provisional Government until the October Revolution.

On March 19, the control extended into the military front lines with commissars appointed with Ministry of War support.

The Bolsheviks rapidly assumed the mantle of the official opposition, and took advantage of the new socialist presence in the Cabinet to attack them for the failures of the Provisional Government.

Kerensky ordered the distribution of 40,000 rifles to the workers of Petrograd (some Red Guards), many of which ended in the hands of Bolshevik groups.

On October 6, with a German advance threatening the city, the government - after advice from the military – made plans to evacuate to Moscow.

The Ispolkom and the Provisional Government had been cut out of control of the forces in the Petrograd Military District, since very few of them remained loyal to them.

The Military Staff was sidelined on the night of October 21, when the Milrevcom took exclusive control of the garrison in the name of the Soldiers' Section of the Soviet.

The District Commander, Colonel Polkovnikov, refused to allow this control, and he and his staff were condemned in a Milrevcom public statement as "a direct weapon of the counter-revolutionary forces".

That night, the Bolsheviks took control quickly and easily, since the vast majority of both the guard and the workers had sided with them, participating in the plans of the "Milrevcom".

The following morning at 10 am, the Milrevcom issued an announcement written by Lenin, declaring the end of the Provisional Government and the transfer of power to the Petrograd Soviet.