Fellow traveller in the context of "Mitläufer"

Philosopher Martin Heidegger (26 September 1889 – 26 May 1976) joined the Nazi Party (NSDAP) on May 1, 1933, ten days after being elected Rector of the University of Freiburg. A year later, in April 1934, he resigned the Rectorship and stopped taking part in Nazi Party meetings, but remained a member of the Nazi Party until its dismantling at the end of World War II. The denazification hearings immediately after World War II led to Heidegger's dismissal from Freiburg, banning him from teaching. In 1949, after several years of investigation, the French military finally classified Heidegger as a Mitläufer or "fellow traveller." The teaching ban was lifted in 1951, and Heidegger was granted emeritus status in 1953, but he was never allowed to resume his philosophy chairmanship.

Heidegger's involvement with Nazism, his attitude towards Jews and his near-total silence about the Holocaust in his writing and teaching after 1945 are highly controversial. The Black Notebooks, written between 1931 and 1941, contain several anti-semitic statements, although they also contain statements where Heidegger appears extremely critical of racial antisemitism. After 1945, Heidegger never published anything about the Holocaust or the extermination camps, and made one sole verbal mention of them, in 1949, whose meaning is disputed among scholars. Heidegger never apologized for anything and is known to have expressed regret once, privately, when he described his rectorship and the related political engagement as "the greatest stupidity of his life" ("die größte Dummheit seines Lebens").

A communist front (or a mass organization in communist parlance) is a political organization identified as a front organization, allied with or under the effective control of a communist party, the Communist International or other communist organizations. It is a structure used by Communist and left-wing parties to intervene in broader political movements. They attracted politicized individuals who were not party members but who often followed the party line and were called fellow travellers.

Vladimir Lenin originated the idea in his manifesto of 1902, What Is to Be Done? Since the party was illegal in Russia, he proposed to reach the masses through "a large number of other organizations intended for wide membership and, which, therefore, can be as loose and as public as possible". Generally called "mass organizations" by the communists themselves, these groups were prevalent from the 1920s through the 1950s, with their use accelerating during the popular front period of the 1930s. The term has also been used to refer to organizations not originally communist-controlled which after a time became so such as the American Student Union. The term was especially used by anti-communists during the Cold War.

Jewish Bolshevism, also Judeo–Bolshevism, is an antisemitic and anti-communist conspiracy theory that claims that the Russian Revolution of 1917 was a Jewish plot and that Jews controlled the Soviet Union and international communist movements, often in furtherance of a plan to destroy Western civilization. It was one of the main Nazi beliefs that served as an ideological justification for the German invasion of the Soviet Union and the Holocaust.

After the Russian Revolution, the antisemitic canard was the title of the pamphlet The Jewish Bolshevism, which featured in the racist propaganda of the anti-communist White movement forces during the Russian Civil War (1918–1922). During the 1930s, the Nazi Party in Germany and the German American Bund in the United States propagated the antisemitic theory to their followers, sympathisers, and fellow travellers. Nazi Germany used the trope to implement anti-Slavic policies and initiate racial war against the Soviet Union, portraying Slavs as inferior humans controlled by Jews to destroy Aryan people.