Book by Academician of the Russian Academy of Natural Sciences V.B. Mironov is dedicated to the First World War, the centenary of which is celebrated in 2014. This is a deep, serious study of who was interested in unleashing this massacre of millions of people, which countries took part in it and why, how events developed and what the results of the war were. The book is based on hundreds of documentary sources, testimonies of witnesses and participants in events, analytical materials of scientists, memoirs of politicians and military leaders. Particular attention is paid to events in Russia - from 1905 to October 1917. How the situation in the country developed, why the Russian Empire entered the war, who its allies were, why the monarchy fell, how the Provisional Government acted, how the First World War ended for Russia - the author gives comprehensive answers to these questions. Numerous illustrations help to create a complete picture of the events that took place and show the main characters of the era.