On 7 May 1941, the Royal Navy captured the German Arctic meteorological vessel "München" and took its Enigma machine intact, this allowed the Royal Navy to decode U-boat radio communications in June 1941. Two days later the capture of "U-110" was an intelligence coup for the British. The settings for high-level "officer-only" signals, "short-signals" ("Kurzsignale") and codes standardising messages to defeat HF/DF fixes by sheer speed were found. Only the "Hydra" settings for May were missing. The papers were the only stores destroyed by the crew. The capture on 28 June of another weather ship, "Lauenburg", enabled British decryption operations to read radio traffic in July 1941. Beginning in August 1941, Bletchley Park operatives could decrypt signals between Dönitz and his U-boats at sea without any restriction. The capture of the "U-110" allowed the Admiralty to identify individual boats, their commanders, operational readiness, damage reports, location, type, speed, endurance from working up in the Baltic to Atlantic patrols. On 1 February 1942, the Germans had introduced the M4 cipher machine, which secured communications until it was cracked in December 1942. Even so, the U-boats achieved their best success against the convoys in March 1943, due to an increase in U-boat numbers, and the protection of the shipping lines was in jeopardy. Due to the cracked M4 and the use of radar, the Allies began to send air and surface reinforcements to convoys under threat. The shipping lines were secured, which came as a great surprise to Dönitz. The lack of intelligence and increased numbers of U-boats contributed enormously to Allied losses that year.