On a whim, I just watched a DVD from the library, "The Bedford Incident." It's about a U.S. destroyer chasing a U.S.S.R. sub. It was released in 1965 and stars Richard Widmark and Sidney Poitier. It very clearly was the inspiration for some of the earliest TOS episodes, and even the earliest TOS publicity photos (that big glass map with concentric circles we never saw in episodes turns out to be a real U.S. Navy plotting board). Martin Balsam plays the McCoy part -- the roles are almost interchangeable.
It is a powerful and disturbing film. Aside from any TOS connection -- and there are many -- I highly recommend it.
It is a powerful and disturbing film. Aside from any TOS connection -- and there are many -- I highly recommend it.