By 1917 the bond between the tsar and most of the Russian people had been broken. Governmental corruption and inefficiency were rampant. The tsar's reactionary policies, including the occasional dissolution of the Duma, or Russian parliament, the chief fruit of the 1905 revolution, had spread dissatisfaction even to moderate elements. The Russian Empire's many ethnic minorities grew increasingly restive under Russian domination.

But it was the government's inefficient prosecution of World War I that finally provided the challenge the old regime could not meet. Ill-equipped and poorly led, Russian armies suffered catastrophic losses in campaign after campaign against German armies. The war made revolution inevitable in two ways: it showed Russia was no longer a military match for the nations of central and western Europe, and it hopelessly disrupted the economy.

Riots over the scarcity of food broke out in the capital, Petrograd (formerly St. Petersburg), on February 24 (March 8), and, when most of the Petrograd garrison joined the revolt, Tsar Nicholas II was forced to abdicate March 2 (March 15). When his brother, Grand Duke Michael, refused the throne, more than 300 years of rule by the Romanov dynasty came to an end.

A committee of the Duma appointed a Provisional Government to succeed the autocracy, but it faced a rival in the Petrograd Soviet of Workers' and Soldiers' Deputies. The 2,500 delegates to this soviet were chosen from factories and military units in and around Petrograd.

The Soviet soon proved that it had greater authority than the Provisional Government, which sought to continue Russia's participation in the European war. On March 1 (March 14) the Soviet issued its famous Order No. 1, which directed the military to obey only the orders of the Soviet and not those of the Provisional Government. The Provisional Government was unable to countermand the order. All that now prevented the Petrograd Soviet from openly declaring itself the real government of Russia was fear of provoking a conservative coup.

Between March and October the Provisional Government was reorganized four times. The first government was composed entirely of liberal ministers, with the exception of the Socialist Revolutionary Aleksandr F. Kerensky (Kerensky, Aleksandr Fyodorovich). The subsequent governments were coalitions. None of them, however, was able to cope adequately with the major problems afflicting the country: peasant land seizures, nationalist independence movements in non-Russian areas, and the collapse of army morale at the front.

Meanwhile, soviets on the Petrograd model, in far closer contact with the sentiments of the people than the Provisional Government was, had been organized in cities and major towns and in the army. In these soviets, “defeatist” sentiment, favouring Russian withdrawal from the war on almost any terms, was growing. One reason was that radical socialists increasingly dominated the soviet movement. At the First All-Russian Congress of Soviets, convened on June 3 (June 16), the Socialist Revolutionaries were the largest single bloc, followed by the Mensheviks and Bolsheviks.

Kerensky became head of the Provisional Government in July and put down a coup attempted by army commander in chief Lavr Georgiyevich Kornilov (Kornilov, Lavr Georgiyevich), but he was increasingly unable to halt Russia's slide into political, economic, and military chaos, and his party suffered a major split as the left wing broke from the Socialist Revolutionary Party. But while the Provisional Government's power waned, that of the soviets was increasing, as was the Bolsheviks' influence within them. By September the Bolsheviks and their allies, the Left Socialist Revolutionaries, had overtaken the Socialist Revolutionaries and Mensheviks and held majorities in both the Petrograd and Moscow soviets.

By autumn the Bolshevik program of “peace, land, and bread” had won the party considerable support among the hungry urban workers and the soldiers, who were already deserting from the ranks in large numbers. Although a previous coup attempt (the July Days; q.v.) had failed, the time now seemed ripe. On October 24–25 (November 6–7) the Bolsheviks and Left Socialist Revolutionaries staged a nearly bloodless coup, occupying government buildings, telegraph stations, and other strategic points. Kerensky's attempt to organize resistance proved futile, and he fled the country. The Second All-Russian Congress of Soviets, which convened in Petrograd simultaneously with the coup, approved the formation of a new government composed mainly of Bolshevik commissars.