Patrol 05 - 03.04.1940-26.04.1940
03.04.1940 U-47 departs dock at Wilhelmshaven. The crew have received no leave, and the minor repairs have been rushed to be completed. Prien has orders to reach his operational area while remaining unseen. This patrol takes place during the Norwegian campaign, codenamed Operation Weserbung. Defective torpedoes cause this to become U 47's first unsuccessful patrol. Prien and his colleagues are more often than not left watching salvo after salvo either explode prematurely or trickle harmlessly away from their intended targets.
??.04.1940 111 heavy and 298 small bombs fall on the fringe of U-47's station. They are dropped by German bombers attacking a flotilla of enemy ships which are on their way to attack the German troops and light naval forces holding the Norwegian coast. One of these bombs causes a leakage of fuel from U-47's starboard diving tank, which is blown to remove any further fuel that might betray their position.
??.04.1940 U-47 sights battleships, a heavy cruiser and destroyers and prepares to attack. An unexpected manoeuvre by destroyers forces the U-boat to dive.
??.04.1940 U-47 sights the cruiser Southampton. Destroyers once again force the submarine to dive. U-47 then runs aground, and has to wait for hours until the ships on the surface have dispersed before it can free itself.
15.04.1940 Sometime late in the evening, in Bydgenfjord near Harstad, U-47 sights a stationary and overlapping fleet which consists of three large transports, a French cruiser, another cruiser and three freighters. The vessels range between 750 and 1,500 yards away. Four torpedoes, set for 12 and 15 foot depths, are fired at these sitting ducks. Inexplicably, all four devices fail to achieve any results.
16.04.1940 Shortly after midnight both Prien and the First Watch Officer check the torpedoes personally. They recheck the fire control data then fire four more torpedoes with the same depth settings as before. Three torpedoes set for impact detonation only (AZ or Aufschlagzndung setting) fail to detonate, while the fourth air-driven G7a swerves at an angle of 10 degrees to the right and explodes against a rocky cliff in front of a cruiser. To add insult to injury, the keel of U-47 becomes stuck on the fjord bed. Prien orders both engines to be run at full speed astern and that the crew should run from side to side to rock the boat. He also orders the Second Watch Officer to destroy all papers and set the scuttling charges in case they should be captured. Water is drained from the torpedo tubes and pressure tanks, and the crew continue to stamp from side to side for a few minutes. Prien then orders the starboard engine stopped, the rudder aport, and then the starboard engine half-speed forward. U-47 damages its starboard engine in attempting to free itself. Just as an armed trawler appears on the scene, U-47 rocks to an even keel and is able to dive. According to Prien the trawler is blocking their path. U-47 dives a thousand yards from the trawler, passes under it and manages to escape from the fjord. Depth charges are heard to explode behind them.
19.04.1940 At a range of nine hundred yards, U-47 fires twice at the battleship Warspite. Both set for magnetic detonation (MZ or Magnetzngdung setting), neither find their mark. Pursued by two British destroyers, Prien and the crew of U-47 escape by the skin of their teeth.
20.04.1940 With a record of ten duds from ten shots, Prien refrains from attacking a convoy south-west of Westfjord. Later he explained his decision to Dönitz, flatly commenting that he "could hardly be expected to fight with a dummy rifle". NB. Although he had four of his fourteen torpedoes left, Prien writes in U-boat Commander (Tempus Publishing Ltd), which is an English translation of the 1940 publication Mein Weg nach Scapa Flow (Deutscher Verlag, 1940), that he only had one torpedo left at the end of the patrol. This was so that he wouldn't have to explain to the wartime German public why he later returned from this patrol with four torpedoes remaining.
26.04.1940 U-47 returns to dock at Kiel.
Total days at sea: 24
Enemy vessels sunk: 0
Total days in port: 38