Karl Mannerheim is one of the most famous political figures of the XX century. Lieutenant General of the Russian Imperial army, after the revolution of 1917, he fled to Finland, where he became a field marshal of the Finnish army, and then president of that country. Under Mannerheim's leadership, a powerful defensive line was built in Finland, named after him, during the Soviet–Finnish War of 1939-1940. it significantly hindered the offensive of the Red Army. During the Great Patriotic War, Finland sided with Germany against the USSR, but in 1944 concluded a peace agreement with the Soviet Union and began military operations against Germany. In his memoirs, Karl Mannerheim describes his service at the court of the last Russian Emperor Nicholas II and in the Russian army, the revolution in Russia, the difficult relations between Finland and the USSR in the interwar period, the Soviet-Finnish War of 1939-1940 and the war of Finland with the USSR in 1941-1944. Special attention is paid to the imperial aspirations of Russia and the USSR, as well as the place of Russia-USSR in European politics.