Arno Joseph Mayer is a Luxembourg-born American historian who specializes in modern Europe, diplomatic history, and the Holocaust, and is currently Dayton-Stockton Professor of History, Emeritus, at Princeton University. A self-proclaimed "left dissident Marxist", Mayer's major interests are in modernization theory and what he calls "The Thirty Years' Crisis" between 1914 and 1945. Mayer posits that Europe was characterized in the 19th century by a rapid modernization in the economic field by industrialization and retardation in the political field. He has argued that what he refers to as "The Thirty Years' Crisis" was caused by the problems of a dynamic new society produced by industrialization facing a rigid political order. He feels that the aristocracy in all of the European countries held far too much power, and it was their efforts to keep power that led to World War I, the rise of fascism, World War II, and the Holocaust.