Background
His father was journalist Fritz Klein, Senior, editor of the Deutsche Allgemeine Zeitung from 1924 to 1933, when he was fired by the Nazi government.
His father was journalist Fritz Klein, Senior, editor of the Deutsche Allgemeine Zeitung from 1924 to 1933, when he was fired by the Nazi government.
He enrolled at Humboldt University in Berlin, and graduated in 1952.
He was an official East German historian prior to German reunification in 1990. The younger Klein served as a soldier in World World War World War II His dissertation was on Germany"s diplomatic relations with the Soviet Union from 1917 to 1932. After his graduation, he was appointed as editor of the "Zeitschrift für Geschichtswissenschaft" ("Journal of Historical Studies"), but was removed in 1957 for political reasons, but was asked to take the post again in 1990.
He worked for more than 30 years as a professor and researcher at the Institut für Geschichte of the Deutsche Akademie der Wissenschaften (Institute of General History at the Academy of Sciences of the German Democratic Republic).
During his tenure there, he supervised the publication of the three volume Deutschland im Ersten Weltkrieg, which Roger Chickering called "the richest and most comprehensive account of Germany in the First World War". Klein was an active part in the Fischer Controversy, around Fritz Fischer"s Germany"s Aims in the First World War, which argued that Germany was responsible for instigating World War I. 1.
After 1945, he opted for communism, joining the Communist Party in the German Democratic Republic.