Oshima in Berlin

In 1934, Colonel Ōshima became Japanese military attaché in Berlin. He spoke almost perfect German, and was soon befriended by Joachim von Ribbentrop who was Hitler’s favorite foreign policy advisor at that time. Promoted to major general in March 1935, under Ribbentrop’s guidance, Ōshima met privately with Hitler on a number of occasions. With the support of the Nazi leadership, Ōshima progressed rapidly while in Berlin, attaining the rank of lieutenant-general and being appointed ambassador to Berlin in October 1938. In September 1939, Ōshima was recalled to Japan as relations between the German and Japanese governments were strained following the conclusion of the German-Soviet non-aggression pact; however, at the insistence of the Nazi government, he returned to Berlin as Japanese Ambassador in February 1941, and remained in that position until the German surrender in May 1945. He dedicated his efforts until the end of the War in Europe to building closer relations between the two countries. Such was his fanaticism to the Nazi ideology that the American journalist William L Shirer in his book The Rise and Fall of the Third Reich wrote that Ōshima “was more Nazi than the Nazis”.

Ōshima’s close relationship with Hitler and Ribbentrop gave him unparalleled access for a foreigner to German war plans and national policy. In turn, Hitler admired the militaristic Japanese and made Ōshima a personal confidante. As a measure of the value of Oshima as an intelligence source, in August 1943, through him, Britain and the US learned that the Luftwaffe had been instructed to step up production of aircraft giving priority to fighters rather than bombers. Again, in October Oshima reported that Hitler was considering concentrating on the British and US forces rather than the Soviet. The last time that Oshima met Hitler was on 29th May 1944, just days before D-Day, having met Admiral Donitz just a few days previously.

Ōshima made visits to the Eastern Front and the Atlantic Wall and he met periodically with Hitler and other Nazi leaders. He may well have met Rommel. A meticulous military officer by training, he wrote detailed reports of the information provided to him by the Nazis and promptly reported in full by radio to Tokyo in the Japanese “Purple” diplomatic code. Unknown to the Japanese, the Purple code had been broken by American cryptanalysts in 1940 with the result that Oshima’s reports were being read almost simultaneously by those who had access to Magic intelligence. Often, they were able to read them before the Japanese did, as transmission problems between Germany and Japan often delayed cables for hours.

What an odd world we have lived in. Much of the intelligence gained by Eisenhower on the Atlantic Wall defences came from Oshima’s reports rather than from Enigma. “Fish” has been credited with being an invaluable resource of D-Day intelligence but one has only to look at the date that Colossus was introduced to realise its limitations.

PWC Dec 2014