Nicholas II
They fought to overthrow the Provisional government and established communism in Russia.
Operation Czar Overthrow: Revolutions (Russian edition)
That overthrow was called the February Revolution.
Technically he abdicated the thrown in 1917.
Lenin and his group members are the ones who lead the 1941 Russian revolution to overthrow the czar.
It was WWI when Czar Nicholas II of Russia was overthrown. The year, 1917. the following year, he and his entire family were assassinated.
the fought to overthrow the czar and establish communism
Vladimir Lenin and the Bolshevik Party did, but it was not "after the overthrow of Czar Nicholas II." Immediately after the Czar abdicated and his government collapsed, a Provisional Government of ministers was set up temporarily until a new constitution could be written. In October 1917 (Old Style, November 1917 New Style) Lenin set up the communist government after overthrowing the Provisional Government. In addition, it wasn't really "communist" except in name only. It was socialist.
Russia overthrew the Czar in the February Revolution of 1917. The actual date when Czar Nicholas II signed the letter abdicating his throne was March 2, 1917 according to the Russian calendar, March 15, 1917 according to the western world's calendar.
Lenin and his Communist party did not have a large part in the resignation of the Czar in 1917.
The Russian Revolution
Czar Nicholas II signed the October Manifesto after the 1905 Russian Revolution. It promised many personal freedoms, but he soon reneged on all of them leading to his eventual overthrow in 1917.