How important was Vietnam to Japanese success in the Pacific?

Da Pwnzlord

Banned
Could Japan have chosen to invade Indonesia instead of Vietnam in late 1940? How important were the bases in Vietnam to a invasion of the DEI? IOTL, the Japanese invaded Vietnam and Vichy France did not offer much in the way of resistance. It did however raise tensions between the west and Japan, resulting in the oil embargo against Japan, and ultimately Pearl Harbor. It seems plausible that Japan could strong-arm the orphaned Dutch colonies into giving the Japanese basing rights and then invade, just as they did to French Indochina. It would probably cause the U.S. to take a harder line against Imperial Japan as per OTL, but now they can't take away the IJN's oil.

Or (and this was the main point of this post :eek: ) are the bases in French Indochina necessary to make an invasion of Indonesia logistically feasible? Was there some resource in French Indochina just as important to Imperial Japan as oil?
 
I wouldn't say an invasion of the DEI would be entirely logistically infeasible without French Indochina, but certainly, the historical primary assembly point for the Japanese Southern offensive was Cam Ranh Bay. And the Japanese specifically targetted and built up the anchorage which was basically undeveloped under the French for the purpose of supporting their anticipated attacks South, suggesting it was pretty important to their plans.

More important is the question of air cover. Bases in Indochina were used to cover the attack against Malaya, and new bases seized there were used to isolate the British at Singapore before the Japanese committed troops to an attack on the DEI. It's one thing if somehow the Japanese are able to get the Dutch to acquiese to their demands without fighting, but an out and out attack could only be done if the Japanese commit everything, including the First Air Fleet as the attack cannot be covered by land based air. And that would be extremely risky, as it leaves the British at Singapore and the Americans at Manila both able to cut off more or less all of Japans forces at will if they react to the attack fast enough.
 

Da Pwnzlord

Banned
Did the British have any forces in Singapore to threaten the Japanese with? September 1940 (invasion of French Indochina) is when everyone's panicking over Sealion. IIRC the commitment of just two capital ships in the form of Force Z was not done lightly by the British.

I don't think the U.S. would go to war over the DEI. They didn't over Vietnam, China's lifeline to the outside world, why would they rush to the assistance of the Dutch?
 
Did the British have any forces in Singapore to threaten the Japanese with? September 1940 (invasion of French Indochina) is when everyone's panicking over Sealion. IIRC the commitment of just two capital ships in the form of Force Z was not done lightly by the British.

I don't think the U.S. would go to war over the DEI. They didn't over Vietnam, China's lifeline to the outside world, why would they rush to the assistance of the Dutch?

Da Pwnzlordd

Depends on the exact timing. Don't forget they only occupied the southern part of FIC in ~July 41.

However the key point is that without bases there the Japanese can not realistically attack Malaya. As such if they do something that makes Britain decide it has to respond Malaya can be fairly quickly reinforced and units operating from there can be very dangerous to the Japanese. Not in the short term surface ships but subs and possibly some a/c could operate against Japanese supply lines, especially if the Japanese were trying to invade DIC at the same time.

I'm not so sure that the US would have stayed neutral in such an event as possession of DIC would have put Japan in a much stronger economically position. It may have still stayed neutral. However the key point is not what the US would have done but what the Japanese thought they would have done. With the US fleet and even more importantly the steadily growing forces in the Philippines the Japanese decided they couldn't risk the US not coming off the fence if they struck south.

Steve
 
Japanese occupation of French Indochina was possible because it had the cover that Vichy "agreed" to it. Japanese actions there would not lead to a war which an invasion of the Dutch East Indies would. Vichy did not need Indochina. The Dutch government in exile absolutely needed the East Indies.

Occupying Indochina also enabled the Japanese to cut off another supply route to Nationalist China.

An immediate move against the Dutch East Indies would not do that. It would also place Japanese troops there in danger of being cut off, as the Japanese do not control either Indochina or the Philippines.
 
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