Copy No. ___ of 3.
  Op-16-Z  
  A16-2(4)/EF 30  
  S E C R E T  
                                                                                           20 November, 1943.  
     
  MEMORANDUM for Commander Knowles,  
                                      F-21 (Cominch).  
     
     
  Subject:        Airplane Carrier, Attack on by U-664, dated 8 August, 1943.  
     
  1.  The following statements were made by three survivors from U-664, who are believed to be reliable, and is forwarded in connection with your conversation yesterday with Mr. Howland.  
     
  2.  After having been attacked early Sunday morning, 8 August, by two airplanes from a carrier, U-664 submerged.  While submerged, propeller noises were heard on the multiple hydrophones at about 2200.  A radio electrician servicing the hydrophones stated that these noises originated from a ship with three propellers.  Later it was thought that this was the ship which U-664 attacked about two (2) hours later.  
     
  3.  At about 0010, 9 August, U-644 surfaced and at 0030 a large steamer was sighted.  The crew was ordered to battle stations.  Uncertainty exists among survivors as to whether this steamer was an airplane carrier or a tanker.  General opinion is that C.O. knew that it wa an airplane carrier but that the crew was told it was a tanker.  
     
  4.  At 0400 a spread of 3 torpedoes was ordered fired; only two, one of them a F.A.T., were said to have left the forward tubes.  No hits were observed nor explosions heard.  A torpedoman's mate states that the speed of the target was underestimated, being estimated at about 6.5 knots, whereas actual speed was believed to have been about 15 knots.  
     
  5.  After firing at the steamer, a destroyer was seen, appearing aft of the target.  U-664 was then turning to bring her stern tube to bear.  At about 0055, an acoustic torpedo was aimed and fired at the destroyer.  
     
  6.  U-664 waited, still on the surface, for about 17 minutes, then dived.  It was stated that the torpedo would run for exactly 15 minutes; only after that period did the crew feel safe that the acoustic torpedo would not run around and hit the U-boat.  
     
 
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  Op-16-Z  
  A16-2(4)/EF 30  
  S E C R E T  
     
                                                                                           20 November, 1943.  
     
  Subject:        Airplane Carrier, Attack on by U-664, dated 8 August, 1943.  
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  7.  U-664 dived at about 0112, while the destroyer, for this it was believed to be, was approaching.  While the U-boat was submerging, three charges of the S.B.T. were ejected, the first at 80 meters.  At about a depth of 140 meters, a fourth charge was to be ejected, but the mechanism would not work.  
     
  8.  When U-664 had reached a depth of about 180 meters, explosions of 4-5 depth charges were heard; it was stated that they probably exploded above and aft of the U-boat.  No further explosions were heard.  Propeller noises were heard for about 10 more minutes.  
     
  9.  U-664 remained submerged until 1200, 9 August when she surfaced to re-charge batteries, etc.  
     
  10.  All times above are German Summer Time.  
     
     
     
                                                                                   John L. Riheldaffer.  
     
     
     
     
     
     
     
     
     
 
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  1.  BORIE (DD) attacked sound contact 41-38N  38-22W 1907Z/08 - - 16 DC's dropped - - sinking claimed. 
     
  2.  CARD A/C and GOFF (DD) attacked a moving oil slick and sound contact 41-17N  38-40W  1943Z/08 - - 13 DC's - - claimed sinking.