Not to be some sort of downer, but "the Great War" usually referred to World War I, although, I'm not certain that it couldn't be adapted to WWII.

I like the haiku, though.
So-so. I don't think you can go any farther with the limitations a haiku has. I like it.
I like it because I picked up straight away that battleships shoot gunshots and trumpets shoot jazz.

It's just nice when things come easy to you.