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APPENDIX V.

Strength of the Military Expeditionary Force which Japan might, in certain Eventualities, be able to bring against Hong Kong.

MEMORANDUM BY THE GENERAL STAFF.

THE question the General Staff are asked to consider is what number of troops are required for the defence of Hong Hong for the period of one month, during which the Navy cannot guarantee the command of the sea in Far Eastern waters.

The answer to this question must obviously depend upon the nature and scale of attack to which the fortress may be exposed in that period.

2. As long as the Anglo-Japanese Alliance continues, no oversea attack by any third Power of combination of Powers need be apprehended, but once the alliance ceases the situation changes, and for the purposes of this paper it is assumed that Great Britain might not only lose a powerful ally, but find herself confronted by an equally powerful foe.

In view of the position and resources of Japan as a Far Eastern Power and her proximity to Hong Kong, her possible, although fortunately improbable, antagonism forms the basis of the following calculations, as it is held that any defence sufficient to meet a Japanese attack should more than suffice against the attack of any other Power.

3. The Japanese Army consists at present of 19 divisions, 4 cavalry brigades, and some surplus artillery units. It is estimated that ita pesce strength of 219,000 men, with 1,058 guns, is capable of expansion by an additional 783,000 trained men on mobilization. The recent introduction of a two years' term of service for the infantry will cause a progressive increase in these numbers, so that the total strength for war should reach some 1,600,000 in another 16 years.

The war strength of a Japanese division is about 18,300 combatants.

4. In the operations now under consideration the limiting factor appears to be sea transport. The Japanese Mercantile Marine on the 31st May, 1910, comprised 338 steam-ships, each over 1,000 tons gross tonnage, giving a total tonnage of some 979,587 tons. Although it is estimated by experts that not more than one-quarter of this total, or, say, 240,000 tons, would be available for military transport purposes on a sudden outbreak of war, it is conceivable that Japan might collect a certain amount of shipping in her home ports in anticipation of hostilities, and this without our knowledge or without the possibility of active interference on our part.

Moreover, each year will probably see an increase in her Mercantile Marine, so that when our alliance ends in 1915 her resources in this respect are likely to be much greater than they are now.

Taking these facts into consideration, and working on the data afforded by the Russo-Japanese war, it is estimated that in 1915 Japan should be able to command sufficient sea transport at a given moment to enable her to convey from two to three divisions (from 32,000 to 48,000 combatants) in one trip from her home ports to the neighbourhood of Hong Kong.

5. The time taken to mobilize the force should not exceed seven days, and its movement to the various ports, its embarkation there, and the necessary alterations to the transports, should all be effected by the twelfth day. Were it possible to collect and prepare the ships beforehand, the sailing of the force might be accelerated by at least forty-eight hours.

The time taken on the voyage may be set down as five days, and thus the disembarkation, if unmolested, might commence within from fifteen to seventeen days of the receipt of the order to mobilize.

6. The fortress of Hong Kong lies partly on the island of that name, partly on the mainland at Kaulung to the north of the island, and comprises the roadstead and naval anchorage in the enclosed waters that separate the island from the mainland.

For purposes of defence it is therefore necessary to hold two positions, one running more or less east and west across the island, the other on the mainland in the shape of an arc of which the defended waters to the south form to some extent the chord.

7. It is understood that no landing in force is likely to be attempted on the island itself in the face of an adequate submarine and torpedo-boat flotilla, such as it is believed to be the intention of the Admiralty to provide; but it is stated that such vessels will not have the same deterrent effect at a greater distance or in the numerous bays and sheltered waters of the Kaulung Peninsula, which lie to the north-east of Hong Kong, and thus appear to offer the most favourable landing places for an expeditionary force directed against that fortress. Of these, perhaps the most favourable is Talo Harbour, whence a good road and a railway line lead direct into Kaulung, passing the southern extremity of Tide Harbour, which is only 14 miles from the centre of the defensive position on the mainland.

8. This position, some 10 miles long and from 1,000 to 2,000 feet in height, follows the crest line of a series of rugged peaks and is pierced by eleven passes, two of which, the Customs Pass on the east and the Lai-chi-kok Pass on the west, are traversed by roads that can be used by all arms. The remainder have only tracks suitable for infantry and pack artillery.

Although the country over which an attack must be delivered is difficult, it is not impossible, and the exploits of Japanese troops in Manchuria when attacking similar positions show that they would be capable, if in sufficient strength, of succeeding in their attack, unless the position was strongly fortified and held.

9. The force allotted to this front in the present defence scheme consists of about 1,000 infantry, with four 47-inch, two 15-pr., and four 2-95-inch guns and two 5-inch howitzers, and is obviously inadequate for the defence of so extended a front against an attack in strength.

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