Hans Mommsen (5 November 1930 – 5 November 2015) was a German historian, known for his studies in German social history, for his functionalist interpretation of the Third Reich, and especially for arguing that Adolf Hitler was a weak dictator. Descended from Nobel Prizewinning historian Theodor Mommsen, he was a member of the Social Democratic Party of Germany. Mommsen was born in Marburg, the child of the historian Wilhelm Mommsen and great-grandson of the historian of Rome Theodor Mommsen. He was the twin brother of historian Wolfgang Mommsen. He studied German, history and philosophy at the University of Heidelberg, the University of Tübingen and the University of Marburg. Mommsen served as professor at Tübingen (1960–1961), Heidelberg (1963–1968) and at the University of Bochum (since 1968). He married Margaretha Reindel in 1966. He was a member of the Social Democratic Party of Germany from 1960 until his death. He died on 5 November 2015, his 85th birthday. Much of Mommsen's early work concerned the history of the German working class, both as an object of study itself and as a factor in the larger German society. Mommsen's 1979 book, Arbeiterbewegung und nationale Frage (The Labour Movement and the National Question), a collection of his essays written in the 1960s–70s was the conclusion of his studies in German working class history. Mommsen was a leading expert on Nazi Germany and the Holocaust. He was a functionalist in regard to the origins of the Holocaust, seeing the Final Solution as a result of the "cumulative radicalization" of the German state as opposed to a long-term plan on the part of Adolf Hitler. Mommsen is best known for arguing that Hitler was a "weak dictator" who rather than acting decisively, reacted to various social pressures. Mommsen believed that Nazi Germany was not a totalitarian state. Together with his friend Martin Broszat, Mommsen developed the structuralist interpretation of the Third Reich, that saw the Nazi state as a chaotic collection of rival bureaucracies engaged in endless power struggles.