The St. Nazaire raid would make for a great war film. I'm surprised it hasn't already been made
No Americans in it. It could have been made in the 50s, 60s or the early 70s as a British production but since then, and up until very recently, the financial reality of the movie business has been that unless it appealed to American audiences, there wouldn't be the budget to make such a film with decent special effects.
CGI has radically reduced the costs of doing believable special effects, and the international market is a bigger proportion of a film's revenue, so this situation appears to be changing. Good.
Also, when done correctly, CGI is indistinguishable from reality. You see great CGI all the time; it's just that you don't recognise it because it's seamless. Humans are still very difficult to do without the plunge into the "uncanny valley" but machines, action and explosions are all fantastic now.
I know a bit about this stuff as I have a Computing degree, did Computer Graphics in 3rd year and keep up with the state of the art.
https://en.wikipedia.org/wiki/Uncanny_valley
Cheers, Neilster