CHAPTER VIII (continued)
OTHER SHORT SIGNALS: after March 1943.
Dolphin (Narwhal), Plaice, and Grampus all carried occasional B-bars from U-Boats, but these were not used cryptographically.
The later history of long E-bars is at least of amusement value. A certain number of practice E-bars were sent on Dolphin and Practice keys but on Shark E-bars were only sent on two occasions.
(1) In July 1943 the boats asked to send dummy B bars from mid-Atlantic were also asked to send dummy long E-bars - an absurd practice since they were never (at that time) used when activity was taking place.
(2) In September 1943 - when 5 signals on Shark frequencies disguised as long E-bars were sent to escaped German prisoners of war in America. The letter count of the messages showed them to be on a hand cypher involving (at some stage) a simple substitution.