The Dimensions of German Aid to Japan

Japanese Type B submarine visits Germany in 1942 

To give a quantitative picture of German assistance to the Japanese is impossible. It is clear that German deliveries were drastically limited by the shipping problem, just as were shipments from the Far East to Europe. The chief means of transport, in the absence of Japanese vessels, were the German and Italian blockade-breakers which went to the Far East to pick up raw materials for Germany. There is evidence that some of these ships departed for the Far East without being fully loaded. Presumably, the delay in negotiating the Japanese requests in Berlin or in obtaining delivery from the German manufacturer explained this situation. Since the ships were German and Italian and not Japanese, it is understandable that they followed a shipping schedule determined by German rather than Japanese needs and departure times.

During the 1941-1942 shipping season, eight ships reached the Far East; they carried a total cargo of 32,500 tons. During the 1942-1943 season, another eight ships reached the Far East, with a total cargo of 24,447 tons. No tabulation of losses incurred en route to the Far East is available. Originally, seven ships were slated to leave for the Far East during the 1943-1944 season, but in view of the heavy losses of ships returning from Asia during the previous shipping season and the general hazards of blockade breaking at the time, it is unlikely that more than one or at most two ships left. Whether any arrived is not known.

After the second half of 1943, a total of twenty submarines reached the Far East in order to take cargo back to Europe. As some of the boats carried out assignments in the Indian Ocean before going to Japan, they could not have carried a full load of cargo. Nor did any of the Japanese submarines used in blockade breaking succeed in making the return trip to Japan. The total number of boats being limited, their capacity small, and the imports desired by the Japanese difficult to crate and pack on a submarine, Japan must have derived little benefit from this phase of blockade breaking.

The maximum freight that reached Japan by sea during the period 1941-1944 was therefore in the neighborhood of 60,000 tons, roughly two-thirds of the amount that reached Germany on the more numerous voyages from the Far East. How much Germany had sent to Japan over the Siberian route prior to its closing is not known, but the amount probably did not match what the Germans received, since the Japanese government’s program was only presented in early 1941 and not acted upon for another fifteen months.

Because of the kind of commodities acquired by the Japanese, a description in terms of amounts would be less informative than similar information about the German imports. A full description by type, though it would mean more, cannot be given, since the German and Japanese data are incomplete. It is possible, however, to indicate the general areas in which Japanese purchases were strongest, to list some of the more important German products disclosed and sold to the Japanese, and to indicate in very general terms the value which these purchases seem to have had for the Japanese war economy.

The Germans shared with Japan a number of manufacturing techniques useful to the Japanese war economy—such as a special Krupp process for making cartridge steel and methods for the construction of barrel linings and for electric welding in the construction of naval vessels. Among finished war implements, the Japanese requested and obtained several pieces of artillery—the 10.5-centimeter and the 12.8-centimeter antiaircraft guns, Germany’s famous 8.8-centimeter antiaircraft and antitank guns, and a 7.5-centimeter antitank piece. Some lighter artillery, including two types of machine guns, was also acquired by the Japanese. In view of Japan’s general inferiority to Germany in artillery, all these acquisitions had great potential value to Japan. The value of the 10.5-centimeter antiaircraft gun was enhanced when Germany made available to her ally the combination radar-optical range finder and director which went with this caliber and which the Japanese could not match in quality.

Though it is not known what use Japan made of them, articles from the German optical industry must have been of great value to her. The German records disclose that numerous Leica cameras were given to the Japanese for reconnaissance, especially air reconnaissance, though manufacturing licenses and blueprints seem not to have been divulged, at least not by Leitz. The Japanese acquired a bombsight (specifications unknown), which was probably better than their own, though not as good as American models. A German stereoscopic range finder was also of great potential value.

Germany shared with Japan some of her developments in the radar field and in anti-enemy radar devices. Copies of the Würzburg and Rotterdam sets were turned over to the Japanese as was a homing device (unidentified).

In 1944, a Tiger tank was sold to Japan. The Allies commanded the Mediterranean Sea and Atlantic, so underwater shipping was the only way to get the Tiger to Japan, but few vessels could carry a 30-ton hull. Submarine aircraft carriers that had corresponding characteristics were not complete, and the Tiger would have trouble reaching Japan. Most optimistic estimates put its arrival in December of 1944.

Despite these difficulties, the tank was sent to a Bordeaux port In February 1944, and the Japanese paid for the order: officially coming into possession of the Tiger, but not able to use or reverse engineer it. With no way to ship it, the tank remained in France until the summer of 1944, when the Allies landed in Normandy and put Germany on the spot.

On September 21 1944, on the authority of the Supreme High Command of the German Army, the Japanese Tiger was leased (or requisitioned, according to other sources) and passed to the field forces where it was lost somewhere on the Western Front. In view of Japan’s inferiority in armor, reproduction of the Tiger tank in Japan might have become significant in the event of an Allied landing and protracted fighting on the Japanese home islands.

Among items for the Japanese navy, the Germans turned over a gun stabilizer for surface ships. This should have been very beneficial to the Japanese, who, though generally competent in gun control, were outclassed in this respect by the Germans. For that reason, too, the Japanese may have benefited from a torpedo fire control unit for surface ships which should have enabled them to make better use of their already excellent torpedoes. Further, Germany made available a 750-ton submarine hull, which probably aided Japanese ship designers since the German model was more pressure-resistant than any Japanese design. Finally, the Japanese acquired the German navy’s automatic E-switch, a control device for computing and adjusting fire against enemy aircraft. Its use would have remedied a pronounced Japanese weakness.

Equipment for the Japanese air force would seem to have been of less value. Japan acquired specimens of the fighter planes Me-109 and FW 120, which probably were better than her own comparable types, although the United States had learned halfway through the war to cope with these planes on the European theater. A pursuit plane, the Me-163, and the jet Me-263 were also given to Japan. However, like Germany herself, Japan did not obtain and produce the jet early enough in the war to enable its superiority to offset the enemy’s greater numbers.

During the early war years, the Germans released to Japan only those items which had passed beyond the development stage. Japan was offered access to V-1 and V-2 data but refused the latter. Whether she acquired data on the submarine Schnorchel is not known.

It is difficult to measure the benefit which Japan derived from the German samples she acquired and the occasional manufacturing data she procured. Reproduction of the German-made items in Japan seems to have presented greater difficulties than either Germany or Japan at first expected. Possibly this was because Japanese engineers were not skillful enough and German technicians were sent to Japan only in rare cases. Shortages in labor and raw materials may also account for Japan’s failure to make better use of the German samples and data.

Two examples illustrate this point. In 1943 Germany had presented Japan with two submarines. These were to be examined and copied to enable Japan to wage a more effective warfare against enemy merchant shipping, presumably mainly in the Indian Ocean. Of the two boats one was lost en route to the Far East, the other one was gratefully received, and even acknowledged in a personal telegram from Hirohito. Production of the boat, however, was never begun in Japan.

Another notable example of the failure of technological assistance is the case of the German jet plane Me-263, then the only military jet in the world. A specimen of the Me-263 was acquired by the Japanese in 1944. When the plane and the accompanying Messerschmitt technicians were lost en route from Singapore to Japan, the Japanese tried to construct the plane from the blueprints, which had been flown ahead. Numerous delays occurred and instead of having the plane in production by March 1945, as they expected, the Japanese only flight-tested the first craft in July. It crashed. The story is told best in the words of the director of Mitsubishi’s aircraft production division:

Investigation disclosed that the engine failure was due to fuel feed stoppage. This was explained as follows: Because of the need for hurrying the test, Yokosuka airfield was used. This was known to be too small for safety so a minimum of fuel was loaded. So small an amount was loaded that, with high acceleration and steep angle-of-climb soon after take-off, the fuel surface dropped below the outlet level and the flow of fuel failed. As a result of this finding the whole fuel system had to be redesigned. The drain part was relocated and enlarged and a jet pump was installed. Before the next prototype engine could be built, however, the Japanese surrender occurred.

Perhaps the Japanese were more successful in copying German products of less revolutionary design. Their representatives in Berlin certainly continued right up to early 1945 to send samples and blueprints to Japan—either by submarine or eventually by military courier via Turkey and the Soviet Union. Since the Japanese did not have to pay for manufacturing licenses and data after March 1944, however, it may well be that their sustained interest in German manufacturing methods reflected what the Germans chose to call “industrial espionage” rather than the expectation of concrete military benefits.

If German technical aid was of limited value to the Japanese services and Japan’s wartime industry, one explanation can certainly be found in the lateness of the aid. The attempt to make up for lost time played a fatal role in the crash of the test jet. Loss of time and delay of negotiations in Berlin also meant that the German designs reached Japan when she was no longer able to take full advantage of them. By 1944, when many of the most important German designs reached Japan, her industry was already too badly disrupted by her disastrous supply situation and the massive American air raids to permit her to put German-made items into serial production.


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