740.0011 Pacific War/1877
Memorandum by the Adviser on Political Relations (Hornbeck)
French Indochina: Political and Military Strategy: Certain Considerations
French Indochina has been, is, and may increasingly be of great value to Japan in the prosecution of Japan’s war effort.
French Indochina is, by virtue of its location, an area of great strategic importance as regards radial operations in which, in her present [Page 757] plan, Japan is engaged, on land, on water, and in the air. (Note. Incidentally, in addition to current indications afforded by Japan’s present plans of military operation, reports from Moscow have given an account of a Japanese map in which the island of Formosa has been made a center from which the Japanese have drawn a circle with a 4,000-kilometer radius—which is taken to be an indication of a Japanese geographical-political-military concept. Northern Indochina lies about 1,300 kilometers from the center (Formosa) fixed upon for the purpose of that map and 2,700 kilometers inside of the circumference.)
In Indochina the Japanese have acquired, at practically no cost to themselves, good harbors, a few good airports, transportation facilities, barracks and housing, money, and a great variety of important supplies. In that area, the Japanese are compelling 10,000 Frenchmen and 20,000,000 natives to give them assistance of one type or another. From that area, the Japanese have been and are drawing food supplies and raw materials for the use of Japan’s military machine and for use in Japan. From that area as a base, they are conducting naval operations and air operations—and they can, whenever they may choose, conduct land operations.
At present the Japanese are trying by pressure on Vichy and on the French Indochina Government to effect a turning over to Japan of merchant vessels under the French flag.
At present the Japanese are trying by pressure on the French Indochina Government to obtain a promise whereunder the whole of the rice supply surplus of Indochina will be turned over to Japan.
In the light of these facts, it is believed that serious thought should be given to the question which Chinese military authorities have raised whether it might not be highly advantageous in the United Nations war strategy to have Chinese armed force invade Indochina.
The Military Intelligence Division of the War Department General Staff gave an estimate, as of January 20, that the Japanese effective air strength in Indochina, Thailand and Malaya totaled approximately 720 operating combat planes and that favorable lines of communication afforded Japan access to a considerable number of reserves; that Japan’s offensive has thus far been successful because of air superiority; that if that superiority could be denied Japan, her offensive would collapse; that Indochina appeared to be the key to the situation; that Japan’s western flank was open to attack; that to protect that flank the Japanese probably would launch an offensive against Burma; that such action would secure Japan’s position as far as Indochina is concerned and would at the same time close the Burma Road,13 making [Page 758] it difficult to supply air action which might be launched from bases in China against Japan’s lines of communication or against Japan; that strong air and ground action against the Japanese in Indochina from Burma would serve two purposes: (1) defensively, protection of Burma, and (2) offensively, possible driving of the Japanese from Indochina, which would cut Japan’s lines of communication and force a withdrawal from points south of Indochina. They stated that if Allied bombers were based in Indochina, the Japanese Navy would not be able to operate—as its units could not be supplied; and that the least result from such an offensive (against Indochina) would be to relieve pressure in southern Malaya and the Dutch East Indies.
The French of course do not wish to see Indochina become a theater of combat operations. Vichy in particular has been making diplomatic effort toward preventing such a development. It is believed, however, that, if Chinese forces were to invade Indochina, the French in Indochina would not vigorously associate themselves with the Japanese in resistance to the Chinese invading forces. Possible political effect upon Vichy of a Chinese invasion of Indochina must, of course, be given due consideration. It is doubted whether, at this stage, that effect would be adverse to Allied interests. The position of Vichy as between the Axis powers and the Allied powers is pretty thoroughly established: Vichy is ineffective, and Germany is in position almost completely to dictate. Vichy well knows that unless the Allies win the war Indochina is lost to France forever. Vichy therefore has little or no reason to prefer a continued Japanese occupation of Indochina to an occupation thereof by forces on the Allied side.
More than a month ago the Chinese Government communicated to the French authorities in Vichy a memorandum replying to and commenting upon a contention advanced by the French authorities that Indochina possesses a “neutral” status and that the said status should be respected.
[Here follows substance of translation of Chinese telegram printed on page 754.]
It is understood that there are among French armed forces in Indochina some 150 French pilots who are said to be seasoned men and eager to fight. It is doubted whether those pilots would assist the Japanese. It is believed that there is warrant for a surmise that if those pilots once got their planes into the air they would soon disassociate themselves from any connection which they may have had with the Japanese forces; and it is conceived that they might go over to and associate themselves with American, British or Chinese forces operating against Japan in the general theater under reference.
Suggestion has been made, in a discussion of the political aspects of a possible entry of Chinese troops into Indochina, that this venture [Page 759] presumably should be undertaken only if there existed a reasonable expectation of military success.—Consideration of that question presumably would revolve around consideration of what would constitute a “military success”. For a given operation, the condition of “success” may or may not be achievement of a victory. If by an attack in a particular area an enemy can be compelled to divert to that area forces upon which he is relying for important operations according to plan in another area, the operation of attack may be a success even though it may in itself involve a defeat or require an ultimate withdrawal. It is believed that a movement by Chinese forces against Indochina would seriously disturb the smooth working of Japan’s plan of operations and that it might—depending on unpredictable factors—conceivably alter the picture considerably as regards effective use by Japan of Indochina as a base.
The War Plans Division of the War Department General Staff has expressed an opinion, as of January 26,14 that the efforts which French diplomacy is making to prevent possible Allied invasion of French territories is officially inspired, under duress, and for purposes of record rather than representative of French popular opinion and real desire; that the situation in Rangoon and Burma is such as to render an application of pressure from the north desirable toward halting the Japanese advance; that such application of pressure from the north should not be withheld merely because it might partially involve operations against French Indochina; that in as much as French Indochina is in fact occupied by our enemy the associated powers would be justified in striking back through that territory when and if such action appears desirable; that such action would have little if any effect on French reaction in other regions so long as due regard is shown, in the operations, for French interests, such as private property, etc.; and that the British attitude on this question was not known.
Undoubtedly the Japanese offensives against Singapore and against Burma are tremendously facilitated by the fact that Japan has water and air bases in Indochina and is able to feed her armies there and in theaters southward, westward and eastward thereof from supplies obtained there (rice).
If, by a Chinese attack on Indochina, the Japanese could be compelled to withdraw or divert some of their forces from fronts further south for action in Indochina, it is obvious that from such an operation substantial advantage would accrue to the United Nations’ effort. If, further, the Chinese should be able to seize and hold a position in Indochina or to make the Japanese positions there untenable, the advantage to the United Nations’ effort in general would be enormous.
[Page 760]In the light of the facts and the estimates outlined above, it is believed that, on the one hand, this Government and the United Nations’ Staffs and Command should not discourage indications by the Chinese of a desire to operate against Indochina, and that, on the other hand, the Allied Staffs and Command might to advantage give common and intensive consideration to the question whether substantial advantage might not be gained from encouraging the Chinese to make such a move—in the near future, if possible—and giving them as full support as may be practically possible for and in the undertaking of such an operation.