He began his career as concertmaster in film orchestras conducted by Paul Dessau, then played principal viola in Frankfurt and Hamburg.

Back in East Berlin, he shaped musical life in the GDR in several positions, before he focused on composition from 1954, composing political songs and operas raising social awareness.

From age six, he received a thorough and varied musical education at the Spangenberg Conservatory in Wiesbaden, studying violin, voice, piano, trumpet, timpani and harmony until 1925.

[3] He worked as concert master in Wiesbaden for the UFA film orchestra in 1926, and in the same position for the Alhambra [de] cinema in Berlin from 1927 to 1930,[2] collaborating in both locations with conductor Paul Dessau.

In his stage works, Forest focused on historic topics, pointing at social conscience, such as fascism, war and the atomic bomb.