Nitpicker.
I know you don't mean to, but readers may take your thought to mean that the Communists overthrew the Czar.
They most certainly did not. They took over from the democratically elected Duma, and the government of Prime Minister Kerensky, a true parliamentary democracy. The Czar was already gone.
The Communists had discipline, were absolutely united behind their plan, and they had overwhelming force where they needed it to terrorize their opponents. Had the Russian democrats been able to get their act together and been united, IMHO the Communists would have disappeared in the Russian Civil War, and, in fact, almost did.