> So what were Trots listening to back in the day? Schoenberg?
Do you means Trots in '37-39 or in the 1920s?
Early on that was true with people like Marc Blitzstein who wrote "Cradle will Rock," and later did the Three Penny Opera version that ran so long at the (now) Lortel Theatre on Christopher Street. He was big on Schoenberg and Eisler until the United Front realized the workers weren't too interested in 12-tone music after a hard day at the factory.
His bio is a pretty good introduction to the scene:
Let me know if you read it; I have some recordings of "Cradle" and "Airborne Symphony" I could pass along.
George Avakian told a funny story about taking the Ellington band on a "friendship" tour of Russia in the 1950s. They obliged their hosts by recording a song called "Katyusha" while they were there. When I heard him tell it in 2002, he still wasn't aware that it was a reference to the rocket launchers: quite a song for the Cold War Soviet airwaves!
Best, Charles