This book explores the development of Lenin's thinking on violence, tracing the evolution of his thinking from the late nineteenth century, showing the impact of the First World War, and examining the Bolshevik seizure of power, the subsequent strengthening of dictatorship and "the cleansing of Russia" during the period of the New Economic Policy in the early 1920s. It discusses Lenin's thinking on concepts such as "militant Marxism", "revolutionary dictatorship" and "just war", and argues against the idea that Lenin viewed violence as essential, contending that although his revolutionary ideology did legitimate violence where it was progressive and necessary, external factors, especially oppressive Tsarist rule, the bloodiness of the First World war and the vulnerability of the early Soviet state, played a significant role in the evolution of his thinking. The book also sets Lenin's thinking on violence within the wider context of the development of state violence in the early twentieth century.