The Twenty Years' Crisis( 1919-1939): An Introduction to the Study of International Relations is a book on international relations written by E.H. Carr. The book was written in the 1930 s shortly before the outbreak of World War II in Europe and the first edition was published in September 1939, shortly after the war's outbreak. The text is considered a classic in international relations theory, and is often dubbed one of the first modern realist texts.