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In World War Two, surveillance of enemy communications provided essential material for BP’s Codebreakers and crucial intelligence for the Allies. Once messages had been decrypted and translated at Bletchley Park, the information they contained was meticulously recorded onto index cards. This vast index of data enabled intelligence to be generated on all levels of enemy activity – not just military plans and operations, but also information about individuals. These cards are from an index of Japanese diplomatic messages compiled by the Japanese Military Intelligence Section in Block F. They contain records of senior Japanese and German personnel. Even personal details, such as an officer’s poor health or a family wedding, could provide valuable intelligence on where the enemy was and what they were planning.


This album was first published on 10 July 2020.

Field Marshal Gerd von Rundstedt was appointed German commander-in-chief in the West from March 1942. Here, Bletchley Park records his visit to inspect German defences along the French coast in April 1942. Known as the Atlantic Wall, this extensive system of fortifications and defences was erected from 1942 to 1944, in anticipation of an Allied invasion of occupied Europe.

The reverse of von Rundstedt’s index card reports his dismissal after the Allies’ successful D-Day invasion on 6 June 1944 and the German defeat in Normandy. Also noted is his succession by General Günther von Kluge, although these messages are not recorded in date order. The first rumour of the succession, intercepted on 4 July 1944, was only added to the index card after intelligence from messages later in July had confirmed von Rundstedt’s dismissal and replacement.

In 1942, General (later Field Marshal) Erwin Rommel was commander of the new Deutsches Afrika Korps in North Africa. His card records the Axis capture of Tobruk, a strategically significant port city on Libya’s eastern Mediterranean coast, near the border with Egypt. Taken by the Allies in January 1941, Tobruk was defended successfully through an 8-month siege later that year. It finally fell to Axis forces after a second attack in June 1942.

Later entries on Rommel’s card refer to his posting to France from November 1943, under the command of Field Marshal von Rundstedt. The bottom four lines record the famous incident when Rommel was severely wounded after his staff car was strafed by an Allied fighter plane on 17 July 1944, near Sainte-Foy-de-Montgommery in Normandy. Rommel was hospitalised, but is recorded here as recuperating on the outskirts of Paris by the end of that month.

The Japanese diplomatic index lists not only mentions of military personnel in intercepted Japanese diplomatic messages, but also key civilians. Professor Baeker is noted as studying penicillin at the Robert Koch Research Station. Based in Berlin, the Robert Koch Institute conducted research into infectious diseases that could threaten military striking power.

Japanese personnel were frequently mentioned in their diplomatic traffic, which covered not only military matters but also individuals’ personal circumstances. Major Saburo Kato’s card tracks his health in 1944. Hospitalised in Turkey with a temperature of 100.4 degrees, he is then recorded as convalescing. Several months later, a signal from Tokyo requests a report on his condition.

Yoshisada Shizuno’s card notes his promotion from mechanic to engineer, and that he was paid a remittance of 2200 yen while working in Rome in January 1943. Further cards record his attendance at a technical conference in Berlin, postings in France and Italy, and his marriage on 10 July 1944.

General Oshima was the Japanese Ambassador to Berlin. His reports on high-level meetings with German command, including Hitler, were the Allies’ “main basis of information regarding Hitler’s intentions in Europe”, according to General George Marshall, Chief of Staff of  the US Army. This card records talks with von Ribbentrop, Germany’s Foreign Minister, on the prospect of the Second Front – an Allied invasion of German-occupied Western Europe that had been proposed by Stalin in 1942 in order to relieve pressure from German forces on Russia’s western front.

Other cards in the Japanese diplomatic message index collate information about many different individuals. Messages listed here refer to German personnel and range from the award of several decorations to new appointments and postings, anti-typhus research work, and another set of talks between the Japanese and von Ribbentrop.

Similar compilations exist for Japanese personnel. Many entries on this card refer to the complexities of international travel in wartime. The Argentinian Government are recorded as refusing visas for two Japanese officers, Majors Kaneko and Nishida. Later that year, a warning is sent that if Major Kaneko remains much longer in Lima he is in danger of being interred.

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