Allied signals intelligence that revealed U-boat locations and allowed convoys to reroute?

• A. Bletchley Park code
• B. Blue Book
• C. Ultra intelligence
• D. Red Book

Answer: (C)

Ultra intelligence is the label for the highly actionable Allied intelligence that came from decrypting German communications, including Enigma traffic, during WWII. At places like Bletchley Park, cryptanalysts turned intercepted German radio messages into timely information about U-boat positions, patrol patterns, and departure and routing. This meant Allied planners could steer convoys away from wolf-pack concentrations and assign escorts where they were most needed, dramatically improving convoy safety and tempo.

Other terms describe the codebreaking effort or unrelated collections, not the specific, battlefield‑impacting intelligence product. Ultra was the name for the actionable intelligence that directly informed naval routing and escorting decisions.