The Bolsheviks played a huge part, but it’s important to remember that they didn’t make the revolution happen. The revolution happened, and when it came to the crunch, it was the Bolsheviks who had been much more hands-on with organizing the proletariat, meaning that 1) they could tell strikers to wait for it… and be listened to, and 2) they understood how highly ordinary people prioritized not being sent to die in a pointless imperialist war. Everyone else drank the imperialist Kool Aid eventually, until only the Bolsheviks had any credibility left

It doesn’t talk so much about how the revolution spread so much as how the Bolsheviks took the reins, but October by China Mieville is a very enjoyable read.