Here's an article after my own heart:
A Lost art: The Blue Devils’ French horn lines
The writer marched french horn with Blue Devils just a few years before me so I never met her. It sounds like the line was quite a powerhouse then. Since about 1987 they have been eliminated from BD's horn line however.
There's a discussion about this article in the Drum Corps Planet forums here:
A Lost Art: The Blue Devils French Horn Lines, (New Fanfare column on www.dci.org)
"Yes, this 'goofy looking thing' is a French Horn!" (from a drum corps button available from souvie trucks back in my day)