Hey, I'm not doing History at all but I thought I'd give this a crack.

Paul Dessau was a German composer throughout WWII, wasn't he? So when you think about that and how he was in exile as an anti-Nazi spokesperson, you can see the effect he had on society. As a "traitor" to his own country, he fled to America and helped the American population appreciate the skill of his composition and his anti-Nazi views (he created music for some Hollywood films, Walt Disney, worked with famous dramatist Brecht if you've ever heard about the Caucasian Chalk Circle, etc.) He received international acclaim for his work in music before dying in 1979.
Therefore, Paul Dessau changed society through his music and his connections with Marxism, the American pop culture and the German Democratic Republic.
Paul Dessau's work effected composers internationally, and the use of music in avante-garde films and dramas.
Someone please correct me if I'm wrong, but there's my answer. You can expand on that to get good detail. There's plenty on Dessau's music career on the web, so
here's a link to start you off.