Operation Olympic papers

Should the US have found it necessary to launch a land invasion of the Japanese home islands, the procedure would have been referred to as Operation Olympic. The main landing site was scheduled for Kyushu, although it's obvious that the Japanese either knew that ahead of time or by coincidence they strengthened their forces there, including many suicide planes, boats and torpedoes as part of their forces.

I managed to find some formerly Top Secret papers on the project and will include some bits and pieces of information from those papers here.

From an appendix draft:

”a. The Joint Chiefs of Staff direct the invasion of Kyushu (operation OLYMPIC), target date 1 November 1945, in order to:

”(1)Intensify the blockade and aerial bombardment of Japan,

”(2)Contain and destroy major enemy forces,

”(3)Support further advances.”

”...the Japanese will use all available ground, sea, and air forces to resist a landing on Kyushu and will defend desperately to prevent Allied consolidation on the island.”

The paper makes estimates of enemy forces that would be in place by November 1 and that included 2,300 combat aircraft in tactical units and the same or more aircraft that could be used, mainly in suicide operations. The estimate was that 400 to 500 bomber and fighter sorties “could be launched against us during any 24-hour period.”

”Battleships, cruisers, and destroyers which are still operational at the time would probably be organized into suicide task forces and would endeavor to sortie in a desperate effort to oppose our landings. Submarines, midget-submarines, suicide and small surface craft would be employed in large numbers, but should offer no serious problem.”

Another page says “...suicide attacks would be employed on a lavish scale.”

A different page talks about the battleships, cruisers and destroyers and that they would probably be organized into suicide task forces. “ Such opposition should be quickly eliminated by Allied air and naval power.”

”The Japanese Navy will depend primarily upon its shore defenses (fixed and mobile artillery), submarines, midget submarines, suicide and small surface craft to protest the southern Kyushu area from amphibious attack. These should offer no serious problem, however, judging from their ineffectiveness on past occasions.”

(Memorandum for the President): “...We believe that the only sure way, and certainly the quickest way to force the surrender of Japan is to defeat her armies on the main Japanese islands.... the over-all objective of the Japanese war is 'to force the unconditional surrender of Japan by (1)lowering Japanese ability and will to resist by establishing sea and air blockades, conducting intensive air bombardment and destroying Japanese air and naval strength; (2)invading and seizing objectives in the industrial heart of Japan.'”

”By November 1945 the Japanese situation is expected to be critical; their fleet units in home waters have already been so reduced as to no longer constitute a strategic factor; their air arm is already committing training planes to combat and will probably continue to concentrate on maximum suicide tactics; their ability to move ground forces to Japan from Asia or vice versa is already strictly reduced.”

”The cost in casualties of the main operations against Japan are not subject to accurate estimates. The scale of Japanese resistance in the past has not been predictable. Casualty expectancy rates based on experience in the Pacific vary greatly from the short bloody battle of Tarawa to the unopposed landing at Lingayen. It would be difficult to predict whether Jap resistance on Kyushu would more closely resemble the fighting on Okinawa or whether it would parallel the battle of Leyte.”

(I'll throw in my own comment here. If the Japanese are defending their own homeland area, wouldn't it be logical to assume that their resistance would be at least equal to any they gave anywhere else, if not more? I think it would be a natural and probably correct assumption to make that the resistance would be the highest the US military had yet encountered in the Pacific.)

In a section which was marked “delete all this”, there are some projected figures given. For Southern Kyushu, followed by Tokyo Plain, to mid-1946, 40,000 US forces killed, 150,000 wounded and 3,500 MIA. For a Southern and Northwestern Kyushu attack plan, 25,5000 killed, 105,000 wounded and 2,500 MIA. Four a plan that would include Southern Kyushu, Northwestern Kyushu and the Tokyo Plain, 46,000 killed, 170,000 wounded and 4,000 MIA.

”Under the campaign as planned, it is estimated that the defeat of the Japanese in the Tokyo Plain area and the seizure of ports on Tokyo Bay would be completed by mid-1946. ...the war should be over not later than the end of 1946.On the other hand, we are unable to estimate the time required or the losses that will result in an effort to defeat Japan by isolation, blockade and bombardment without invasion, because of our inability to predict at what stage thereof the Japanese might concede defeat, and because of the possibility that invasion of the Tokyo area would ultimately be necessary. We feel that at best, this strategy will lead to a long war, which would have an adverse effect upon the U.S. position vis-a-vis other nations who will, in the meantime, be rebuilding their peacetime economy.”

The proposed plan, then, was to invade southern Kyushu on November 1, 1945; attack the Tokyo area around March 1, 1946; and continue and exploit the air blockade and bombardment of Japan.”

An rather interesting section includes a news bulletin that was given out after the first test of the atomic bomb. The bulletin said that “a remotely located ammunition magazine containing a considerable amount of high explosive and pyrotechnics exploded.”

My comments

Much of the information in these papers became outdated, however, as it became obvious that the Japanese were building their defenses on Kyushu faster than expected, and were bringing in more troops than expected. Casualty estimates ran around 250,000 possible for US forces, and the numbers could have gone higher than that.

None of this information that I found, though, made any reference whatever to civilian opposition. Much has been made in some sources about the training of Japanese civilians to resist the US forces. I have read things that indicated at least some of the civilians were willing to do their best to take the life of at least one US soldier before they were killed, so this could have increased the casualties to a much higher level than expected.

Thus, the use of the atomic bomb was considered as a way to reduce these expected (and unexpected) casualties. There is a question of just how long a war the US public would have supported. The report made a remark about we would be fighting the war while other nations were beginning to rebuild their countries, putting us at an economic disadvantage. The Marshall Plan might, possibly, have not even come about if we had to keep spending US money to fight in Japan, so the rebuilding of Europe could have been delayed.

There was also concern over the USSR entering the war and how much land they would take over. Relations between the US and Russia were not too good at the time, and a late entry into the war by Russia and land-grabbing by that country could have caused a number of political problems. It was sort of like the race between Russia and the US to snap up the Nazi rocket scientists in Europe, to see which country could get the best and the most as fast as possible.

There doesn't seem to be any way to actually say exactly how long the war would have continued if we had not used the atomic bombs, but it seems likely that it would have stretched on at the very least until the end of 1946, as the report noted, and possibly even longer.

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