When I was a teenager, I had a friend whose father had 16mm sound projector and used to buy and rent 16mm movies from some outfit. His father rented this one (perhaps because the rental price was cheap) and I remember watching this in my friends basement.
This film narrated by Richard Carlson, documents two brutal battles in the Pacific. One was the infamous battle of Palailu (pardon me if I have mis-spelled it) and another battle that I have forgotten. I still recall vividly the real life scenes of Marines unloading flame throwers into tunnels and pill-boxes and then pulling out the hideously charred remains of the dead Japanese soldiers. This was pretty rough stuff, even for kid who grew watching video from Vietnam on the nightly news.
The print my friends father had was in black and white. However, I think I remember seeing this film again years later on "Matinee at the Bijou" and print they showed had some colour sequences.