I'm not an expert of the technology of the time, but wasn't much of the newsreel/documentary footage shot without audio?

Much of the newsreel footage was done without sound, as the portable cameras of the time would have needed a second person recording sound on tape, which wasn't widely available at the time. So not much in the way of battle footage. Any sound was added later as sound effects, sometimes rather poorly. Plus the announcers tended to talk over everything.

There are some examples of raw footage at archive.org, and possibly on youtube. You'll have to dig on that one.

2nd edit to add - Also British Pathe' just released a ton of new footage at http://www.britishpathe.com/ There may be some luck there.

edited to clarify.