This work focuses on Winston Churchill’s changing attitudes towards the Soviet Union. In the first four decades after the Bolshevik Revolution in 1917, he oscillated in a seemingly bewildering fashion between enmity and apparent friendship with the Soviets. Taking the Bolshevik Revolution as its starting point, this is a study of Churchill’s relationship with the USSR until his retirement in 1955. Initially Churchill achieved a high profile as a tireless advocate of Allied intervention in Russia to eliminate the Bolshevik regime; by the late 1930s he was urging Britain to forge a Grand Alliance with the Soviets against Nazi Germany; during the winter of 1939-40, he was apparently willing to see Great Britain come to the assistance of Finland in its war with the Soviet Union; in June 1941 he eagerly embraced the Soviet Union as a worthy ally against Nazi Germany; after the latter’s defeat he rapidly moved to proposing a common Anglo-American front against the Soviet Union and global communism. How can we understand this Churchillian enigma? How was it that Churchill’s relationship with the Soviet Union was so inconsistent?