In 1917, the Socialist Revolutionary Party split between those who supported the Russian Provisional Government, established after the February Revolution; and those who supported the Bolsheviks, who favoured the overthrow of the Provisional Government and the placing of political power in the hands of the Congress of Soviets. Those that continued to support the Provisional Government became known as the Right-SRs while those who aligned with the Bolsheviks became known as the Left Socialist-Revolutionaries or Left SRs. After the October Revolution, the Left SRs formed a coalition government with the Bolsheviks from November 1917 to July 1918, but resigned its position in government after the signing of the Treaty of Brest-Litovsk. The Central Committee of the Left SRs ultimately ordered the assassination of Wilhelm von Mirbach in an attempt to cause Russia to re-enter World War I and launched an ill-fated uprising against the Bolsheviks shortly after. Most members of the Left SRs were promptly arrested, though the majority that opposed the uprising were steadily released and allowed to retain their positions in the Soviets and bureaucracy. However, they were unable to reorganize the party, which gradually splintered into multiple pro-Bolshevik parties – all of which would merge with the Russian Communist Party (Bolsheviks) by 1921.