Operation Frankton is one of the great British raid stories of World War Two - some commandoes canoed up a French harbour and put mines on several ships; they succeeded in sinking a lot of shipping but most of them were captured and executed. It's such a fantastic story that any half-decent treatment of the story was bound to be successful; this is maybe a quarter decent.
It's good some good things going for it: CinemaScope photography, Trevor Howard in the cast, location shooting in Portugal which helps the last act. But it's an odd fish. The uncharismatic Jose Ferrer, during his brief reign as a box office star in the 1950s (he'd won the Oscar and been in a few hits), is bland in the lead as the guiding force behind the mission. Ferrer's got a great speaking voice but the role could have really done with an old fashioned movie star.
More problematic is his direction which feels sloppy. In his defence the movie may have been cut about - the final raid in particular feels all over the shop continuity wise, with Brits canoeing, then getting spotted and escaping, but no security being brought in at port, then some are captured, but others keep going.
There's also massive slabs of comic relief in the first two thirds of the movie - wacky training antics, involving Royal Marines running around in their underwear plus drinking sequences, and Anthony Newley (who would become a staple for Warwick Films, who made this). Plus we get forced conflict between Howard and Ferrer, with Howard barking at Ferrer that he doesn't like the plan (something Howard would constantly do in war films in the 50s and 60s). And there's too much music playing on the soundtrack.
But like I said it's a tremendous story and I was moved at the end, with Howard and his colleagues being lined up against a wall and shot as the explosions go off. And I never met a guys on a mission film I didn't like.