Germany Read Britain's Convoy Code for a Year — London Was Warned and Kept Using It

In the spring of 1943, German codebreakers in Berlin were reading the Allied convoy code - the cipher that told British, Canadian and American convoys where to sail, where to turn and where to meet their escorts. Sometimes, according to British files, they had that information ten to twenty hours in advance. The team was led by Wilhelm Tranow, a former navy radio operator who had broken his first British signal in 1914. His section of the B-Dienst rebuilt Naval Cypher No. 3 and, at its peak, read as much as eighty percent of the traffic. In August 1942 London learned from decrypted German teleprinter messages that the code was compromised. It warned Washington, changed the tables more often - and kept using the book for ten more months, through the hardest convoy battles of the war. This is the same story as our Enigma video, in a mirror: London finally changed its code in June 1943. Berlin never changed its mind. Chapters 0:00 The report from London 1:04 The radio operator 2:37 The convoy code 4:29 Reading along 6:05 The convoys 7:44 The warning 9:43 Doubts in Washington 10:37 The proof 12:04 Two blind spots Sources: Wikipedia (en/de), B-Dienst and Wilhelm Tranow · Ralph Erskine, "Tunny Reveals B-Dienst Successes Against the 'Convoy Code'", Intelligence and National Security 28/6 (2013) · SRH-009, Battle of the Atlantic: Allied Communication Intelligence · Wikipedia, Convoy ON 166, Convoys HX 229/SC 122, Black May · David Kahn, Seizing the Enigma Where the record disagrees, this video says so: how much of the traffic was read in time is still debated - ten to twenty hours ahead in some files, only about one message in ten in time in others; Naval Cypher No. 3 is dated to January or June 1941; U-boat losses in May 1943 are given as 41 or 43. Feldgrau Archive tells the Second World War from the German side of the map - what Berlin knew, what it believed, and what it got wrong. Documented stories from war diaries, signals logs and staff reports. No myths, no glorification. Images in this video are AI-generated reconstructions in the style of period photographs; they illustrate documented events and are not archival footage. Music: original score. #WW2 #BattleOfTheAtlantic #Codebreakers #MilitaryHistory #GermanSideOfWW2