Trotsky was a senior member of the Bolsheviks. He was an excellent student. Trotsky had been active during Russia. He worked with Lenin.
He worked with Lenin then split. Trotsky was spreading world revolution, was exiled many times. In 1917 Trotsky returned back. He was part of unsuccessful revolution that year.
The Bolsheviks took power in October 1917. Trotsky was an important member of the party. The civil war had proved how effective Trotsky was.