World War I and the 1917 Russian Revolution

During World War I, the Russian army was ill-equipped and poorly led by the tsar, and Russia was suffering catastrophic losses in campaign after campaign against German armies. The war showed that the country was no longer a military match for the nations of Central and Western Europe, and it hopelessly disrupted the economy.

In Petrograd, riots over the scarcity of food broke out and Tsar Nicholas II was forced to abdicate. A committee of the Duma appointed a Provisional Government, but the Petrograd Soviet of Workers' and Soldiers' Deputies soon proved to have greater authority. Although the Provisional Government was unable to cope adequately with the major problems afflicting the country (peasant land seizures, nationalist independence movements, and the collapse of army morale at the front) it wanted Russia to continue participating in WWI. On the other hand, the soviets, which were in far closer contact with the sentiments of the people, favored Russian withdrawal from the war on almost any terms.

Aleksandr F. Kerensky became head of the Provisional Government, which was increasingly unable to halt Russia's slide into political, economic, and military chaos. But while its power waned, that of the soviets was increasing, as was the Bolsheviks' influence within them.

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. On October 24 and 25 the Bolsheviks staged a nearly bloodless coup, occupying government buildings, telegraph stations, and other strategic points, and overthrowing Kerensky from power.

References:
"Russian Revolution of 1917." Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 11 2009 .