I am looking for a movie my grandfather showed me back in the 90s.

I am fairly sure…
WWII Movie
Black and White
Probably about American or British military men versus Nazis
Probably 1950s (maybe 40s or 60s)
Maybe the plot had something to do with needing to destroy something. I have faint memory of two men on a small boat trying to attach explosives to something.
The characters in the movie were broken into teams of 2, probably 6 different 2 person teams.
2 men survive at the end, All others are executed or KIA during this “mission”
Whatever this “mission” is they are successful,

Any help would be appreciated. I have spent years thinking about this and trying to find the movie. My grandfather died many years ago and I remember watching this movie and would love to be able to find it.THANKS!!

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