Nolte contends that the great decisive event of the 20th century was the Russian Revolution of 1917, which plunged all of Europe into a long-simmering civil war that lasted until 1945. To Nolte, fascism, communism's twin, arose as a desperate response by the threatened middle classes of Europe to what Nolte has often called the “Bolshevik peril”. He suggests that if one wishes to understand the Holocaust, one should begin with the Industrial Revolution in Britain, and then understand the rule of the Khmer Rouge in Cambodia.