He was a member of the German Communist Party, which he joined in 1926,
though he later told the House Un-American Activities Committee that he
was never really a member as he was never very active in the Party. His
brother Gerhart Eisler, a top agent of the Moscow-controlled Comintern,
reportedly was the USSR's top man in the US during World War II and has
been active as an agent in the US since at least 1933. Ironically, it
was Eisler's sister Ruth Fischer (the former Elfriede Eisler), a German
Communist Party leader and co-founder of the Austrian Communist Party
who had become disillusioned with Stalinism and had been expelled from
the party, who outed their brother. Hans Eisler's fealty remained with
his brother and he denounced his sister. Dubbed "The Karl Marx of
Music," he was deported from the US after being deemed an unfriendly
witness after his 1947 testimony before the House Un-American
Activities Committee. There are substantive claims that Gerhart Eisler
was the man to whom Hollywood communists owed their fealty. After being
deported from the US, he was expelled from Great Britian. (The British
Secret Service had opened a file on Eisler when he briefly lived in
London in 1936 as he associated with many known communists.) He
eventually settled in what became the German Democratic Republic (East
Germany), as did his friend, Bertolt Brecht, with whom he socialized in
Hollywood.
