The Russian Revolution began with the February Revolution in March 1917, when hungry protesters and industrial workers rioted in St. Petersburg. However, the roots of the Russian Revolution stemmed from a lack of faith in the czar. A struggling economy, the disastrous results of Russia's involvement in World War I against Germany and the dissolution of the Russian parliament caused moderates and radicals alike to call for Nicholas II's abdication.
The Russian Revolution effectively removed Russia from the rest of World War I and replaced Russia's monarchy with the first Communist state, transforming the country into the USSR.
The monarchy had been steadily weakening for over a century previous, and Nicholas II had grown increasingly reactionary, dissolving the Russian parliament when it refused to bend to his will. Nicholas II had seen his family assassinated by rebels and responded poorly to the threat of rebellion, inadvertently worsening resistance efforts.
After he abdicated, his brother refused the crown and ended the monarchy. Vladimir Lenin rose to power. The country entered the October Revolution, led by Lenin and the Bolshevik Party. The Bolsheviks formed a new government and installed Lenin as its dictator. However, in 1918, the Bolshevik government found itself embroiled in a civil war against the White Army forces that lasted until 1920. In 1922, the USSR was formed.