Which Allied cryptanalytic intelligence described as decrypted German messages allowing convoy rerouting?

Which Allied cryptanalytic intelligence described as decrypted German messages allowing convoy rerouting?

• A. SIGINT
• B. Blue Book
• C. Red Book
• D. Ultra intelligence

Answer: (D)

Ultra refers to the cryptanalytic work that decrypted German military communications, turning intercepted signals into actionable intelligence. In the Atlantic, this meant Allies could read the German naval codes and know where U-boats were deployed and which routes convoys would likely take. With that knowledge, they could reroute ships to safer lanes or adjust sailing times, dramatically reducing losses and helping win the Battle of the Atlantic. General signals intelligence covers collecting radio traffic but not necessarily decrypting it and turning it into tactical decisions, so it isn’t the specific description asked for. The other terms point to unrelated programs, not the decrypted German messages used to guide convoy routing.

Ultra refers to the cryptanalytic work that decrypted German military communications, turning intercepted signals into actionable intelligence. In the Atlantic, this meant Allies could read the German naval codes and know where U-boats were deployed and which routes convoys would likely take. With that knowledge, they could reroute ships to safer lanes or adjust sailing times, dramatically reducing losses and helping win the Battle of the Atlantic.

General signals intelligence covers collecting radio traffic but not necessarily decrypting it and turning it into tactical decisions, so it isn’t the specific description asked for. The other terms point to unrelated programs, not the decrypted German messages used to guide convoy routing.