Both Germany and Japan were clueless at it though. For example, both seized the necessary oil fields, but both Germany and Japan had no plan on how to utilize the fields once captured. In Germany's case, they had no plan to undo Soviet sabotage nor how to get the oil from the Caucus field to refineries. As for the Japanese, sure they took the DEI oil fields, but had zero idea on how to safely get the oil back to Japan past allied submarines, or once past, into the tanks, trucks, aircraft and ships of their war machine.
As for Italy, instead of seizing unless land around the horn of Africa, why not dig a little in your existing colonies for oil? Libya's oil reserves were discovered by a decade after Mussolini was executed.
We have been over this before. Japan knew exactly what to do with the oilfields, and more importantly the refineries, it captured. And it proceeded to implement its plans immediately war broke oout.
It sent thousands of specialists from its home oil industry to get the fields flowing again in the months after March 1942. One ship carrying these workers was lost in the process. In 1940 the DEI wells produced 65.1m barrels of crude oil. In the year from April 1942 to March 1943 the Japanese reported extracting 25.9m barrels.
Of the 5 major refineries in the DEI, one was captured almost intact (Palembang), two were operating again by Sept 1942, albeit at reduced capacities. Another started limited production in January 1943. And the last had been so thoroughly demolished that it was only restored to operation towards the end of the war. In the year from April 1942 they produced 14.5m barrels of refined products, equivalent to 60% of local crude production, with the focus on increasing aviation fuel over other products. Much of the remainder was shipped to Japan for refining there.
Because they were able to refine so much locally, they had no need to ship all the refined products back to Japan. Instead they could ship much of it direct to where it was needed at bases across the Pacific And during 1942 & 1943 they were been able to increase the tanker tonnage that they had available, through new build, captured vessels and conversion of other types. It was 1943, and particular from Nov 1943, that tanker losses began to mount.
And then in Jan 1944 the IJN moved much of the fleet down to Singapore and Tawi Tawi to place it nearer the oil supplies, and reducing the need for tankers to ship it back to Japan to fill their tanks. Some air crew training was also moved to the DEI for the same reason.
In the 15 months from Feb 1943 the number of US submarines doubled and from Nov 1943 they focussed on the tanker traffic. And of course their torpedoes improved dramatically. That was when the Japanese oil problems really began to kick in.
The Japanese oil problem comes back to the same problem they had on 7 Dec 1941. They needed a quick victory because they knew that if the war dragged on there was no way that they could ever out build US industry.
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