Composer Marc Blitzstein wrote a paean to the short film "Hymn of the Nations" in the form of a letter to the Screen Editor. He wrote that he saw and heard the Arturo Toscanini film in 1944 at a private showing in London for the British Film Unit and its allied counterparts. The film opened in NY at the Little Carnegie the following Saturday accompanying the French-language feature "A Portrait of a Woman."
In 1944 he was serving as music director of the radio station ABSIE (American Broadcasting Station in Europe), still a hush-hush operation. ABSIE was a tool of the psychological warfare department. In the days leading up to D-Day, besides disseminating news and propaganda to occupied Europe, it sought to create the impression that an underground network was in place behind German lines waiting for instruction. Between alerts to this largely imaginary underground, the station broadcast music. One of the first pieces that Blitzstein chose was Verdi's "Hymn of the Nations," from the film's soundtrack.
In his adaptation of the score ,Toscanini interpolated "God Save the Queen," the "Internationale" and "The Star-Spangled Banner." The performance featured the voices of Jan Peerce and the Westminster Choir, Blitzstein said it was a revelation as to what a musical film should be.
Blitzstein was one of a coterie of gay, Jewish political activists in the music world (e.g. Copland, Bernstein, Robbins, Laurents), inexplicably drawn at least briefly to the Stalinist vision, although Blitzstein later said he abandoned the Communist party because he felt it was inhospitable to gays. So did the others.