The intelligence produced by deciphering the Naval Enigma was passed to the Admiralty via the Z Watch in the Naval Section. However, in the early days, they struggled to get the naval commanders to take it seriously but a series of spectacular successes turned things around for the Codebreakers. Throughout the First Battle of the Atlantic, they helped the Admiralty to track the U-Boat wolf packs, considerably reducing the German Navy's ability to sink the merchant navy ships bringing vital supplies to Britain from America.
Nor were the Germans the only targets for Station X - by breaking Japanese ciphers, the Codebreakers were able to monitor the Japanese preparations for war. The suggestion that they knew of the imminent attack on Pearl Harbor but kept quiet in order to ensure America joined the war is nonsense. But their expertise undoubtedly gave great assistance to the American codebreakers.
In 1942, the Codebreakers' many successes also included the North Africa Campaign, when they enabled the Royal Navy to cut Rommel's supply lines and kept Montgomery informed of the Desert Fox's every move. Early 1942 brought serious difficulties with the German Navy’s introduction of a more complex Enigma cipher. But by the end of 1942 they had mastered it as well.