This is an excellent tub-thumper from the war years.<br /><br />John Mills leads a fine cast of regular British B-movie stalwarts in a solo submarine attack upon a fictitious enemy battleship.<br /><br />Filmed in black and white, it's well paced and also well placed considering that a war was going on at the time. If anything, it shows how seriously the authorities took positive propaganda.<br /><br />The mission-side of the movie takes place in genuine submarines. Things are cramped and claustrophobic. The actors look suitably grimy and sweaty without being too offensive to the heroic palate. Other commentators have already drawn attention to the authentic little details like keeping the vessel trim and forgetting to read instruments, as well as the engine-room activities.<br /><br />This probably is the first movie in which debris (and a dead German) is blown from the torpedo tube to fool an enemy destroyer. And it's the ONLY time I have seen part of the vessel exposed in a pretence of sinking - a high risk gamble if ever there was one.<br /><br />I'm a little sceptical as to whether or not a submarine could punch its way through a wire-rope net. Submerged speed was barely twice that of human walking speed, and the net would have had a great deal of 'give'. Also, the engineer was at the same work-station and operating the same levers both on the surface and submerged. This, too, seems implausible as either diesel or electric engines were used and they were in different sections of the ship - or so I'm told.<br /><br />There was a wee bit too much shore-side drama for my tastes. But then, this was a propaganda effort, and clearly contained a subtle message for civilians to mind their behaviour as it could adversely affect service morale and therefor the war effort.<br /><br />These niggles aside, it's a pretty entertaining little adventure. Nowadays movies of such vintage tend to be screened in the afternoon, whilst far more modern and inferior movies enjoy prime-time. But then; it's no longer politically-correct to mention the war in the presence of our European friends (Too many of them have guilty consciences), or our own left-wing fascists (non of whom have ever fought for the freedoms they now take for granted).<br /><br />As a submarine movie it is eminently collectible. Better than 'The Enemy Below', I think, though less demonstrative. Not so authentic as 'Das Boot' by any means, but not so gross either.