this be an excellent tub thumper from the war year . john mill lead a fine cast of regular british b movie stalwart in a solo submarine attack upon a fictitious enemy battleship . film in black and white and it well pace and also well place consider that a war be go on at the time . if anything and it show how seriously the authority take positive propaganda . the mission side of the movie take place in genuine submarine . thing be cramp and claustrophobic . the actor look suitably grimy and sweaty without be too offensive to the heroic palate . other commentator have already draw attention to the authentic little detail like keep the vessel trim and forget to read instrument and as well a the engine room activity . this probably be the first movie in which debris ( and a dead german ) be blow from the torpedo tube to fool an enemy destroyer . and it the only time i have see part of the vessel expose in a pretence of sink a high risk gamble if ever there be one . i be a little sceptical a to whether or not a submarine could punch it way through a wire rope net . submerge speed be barely twice that of human walk speed and and the net would have have a great deal of give . also and the engineer be at the same work station and operate the same lever both on the surface and submerge . this and too and seem implausible a either diesel or electric engine be use and they be in different section of the ship or so i be tell . there be a wee bit too much shore side drama for my taste . but then and this be a propaganda effort and and clearly contain a subtle message for civilian to mind their behaviour a it could adversely affect service morale and therefor the war effort . these niggles aside and it a pretty entertaining little adventure . nowadays movie of such vintage tend to be screen in the afternoon and whilst far more modern and inferior movie enjoy prime time . but then while it no longer politically correct to mention the war in the presence of our european friend ( too many of them have guilty conscience ) and or our own left wing fascist ( non of whom have ever fight for the freedom they now take for grant ) . a a submarine movie it be eminently collectible . good than the enemy below and i think and though less demonstrative . not so authentic a das boot by any mean and but not so gross either .