Who is Howard W. Campbell, Jr. from Mother Night and what is their importance?

Howard W. Campbell, Jr., is the narrator and main character. He was born in Schenectady, New York in 1912. He moved with his family to Germany when he was 11. He grew up to become a writer and playwright. He took a German wife named Helga Noth. He is at heart a rather simple fellow, who loved his wife and his work. During the war and because of his work as a Nazi propagandist, he stuffs his true self deep inside and puts on a façade for everyone. He is so successful at hiding himself, that people only know him as the Nazi he pretends to be. After the death of his wife, Campbell retreats out of the mainstream and begins hiding his physical being, as well.