Two Peter Watkins films here, pioneering examples, perhaps, of what we now call "mockumentaries", documentary-style films of fictional events (here, "The War Game") or past, you-are-there events (Culloden).
As for "The War Game," although it's very much a work from the Cold War era (1965) it's still effective in spite of, or perhaps because of, it being black-and-white, gritty, short in running time, and focused on a small part of a pre- and post-attack Britain. I've seen "Testament," "Threads," and "The Day After" and this seems more effective -- and more graphic -- and while the other three nuclear-attack films show a story, "The War Game" is more immediate. You are watching society coming apart in almost real time, and it's scary.
I differ from other reviewers in that I find that "Culloden" seems to have aged well, if you accept 1964 state-of-the art news media in 1745 as a premise. Given the few actors, and some clever camera angles, the story manages to suggest fragmentary and smoke-shrouded parts of the battle as believable (in a battle that involved 15,000 men in real life). No spectacle, just confusion and the sort of narrow field-of-vision that those caught in such a battle would see, with the participants talking to the camera as the battle unfolds, horribly wrong. The Greek-chorus commentary on the pre-battle failures on the Scottish side does not take away from the story, rather, the viewer is watching an unfolding and inevitable tragedy. Nor does the film neglect the post-battle search-and-destroy by the victorious British forces, in many ways as harrowing as the battle. And you learn something of the participants, famous or not, Scottish, British and Irish (they were there, too, as you see).
Highest recommendation for those with an interest in British/Scottish or cinematic history.