Why did a revolution occur in russia in 1917

The Russian Revolution took place in 1917, during the final phase of World War I. It removed Russia from the war and brought about the transformation of the Russian Empire into the Union of Soviet Socialist Republics (USSR), replacing Russia’s traditional monarchy with the world’s first Communist state. The revolution happened in stages through two separate coups, one in February and one in October. The new government, led by Vladimir Lenin, would solidify its power only after three years of civil war, which ended in 1920.

Andrei karlov was the russian ambassador