How did Ultra intelligence help the Allies fight German U-boats in the North Atlantic?

The Ultra intelligence project was instrumental in the Allied effort to counter German U-boats in the North Atlantic during World War II.

While early code-breaking efforts at Bletchley Park successfully deciphered German air force and army communications, naval Enigma messages remained secure until June 1941. At that time, a team led by mathematician Alan M. Turing finally succeeded in breaking the daily communications of the U-boats.

This breakthrough provided the Allies with critical intelligence regarding the positions of German submarines. By knowing these locations, Allied naval forces could effectively reroute merchant ships to avoid contact, preventing the catastrophic loss of food, munitions, and oil supplies that had threatened to starve Britain. To protect the source of this intelligence, the Allies exercised extreme caution, often leaking false information to suggest that their successes were due to new developments in long-range radar rather than the decryption of Enigma messages.1