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IJA supplies during the Pacific War.

Tables from the United States Strategic Bombing Survey Report No.64 “The Effect of Air Action on Japanese Ground Army Logistics” (1947).

The following tables are explaining, why Japanese generals were so fond of moral factors in combat in preference of material factors. The answer is simple – usually they haven’t got enough of those “material factors”.

And small production of weapons, equipment and ammunition was only part of the problem. They were mostly produced in Japan and had to be delivered across the vast areas of Asia and Pacific to actual battlefields: see last table to find out the amount of supplies lost en route from Japan to front lines.

Note a Japanese term left untranslated in the original: “kaisen-bun” or “kaisenbun” (会戦分), which could be translated as “pitched battle share” or “pitched battle allotment”. This is peculiar IJA unit of measure for the strategical calculations, equal to the amount of supplies standard infantry division will spend during one pitched battle. The battle was supposed to last some 4 months, but active combat was expected to last for only 20 days. One kaisenbun weighted approximately 10000 metric tons and besides c.2500 tons of ammunition it included provision and forage for 1 month (c.7100 tons), as well as c.400 tons of replacement weapons and other supplies. This kaisenbun amount was enough to fight poorly-armed Chinese troops, but against US or British troops IJA routinely had to double or even triple the ammunition and weapons allotment.

1. Index of Amy ordnance production, by category, 1931-45.

Based on 1943 price weights [i.e. in 1943 prices; but 1941 is set for 100% benchmark – Eugen Pinak]

[Note, it is not clear, if the table refers to calendar or financial years (1 April to 31 March of the following calendar year). Probably the later, as it was the year to calculate all budget expenditures in Japan. – Eugen Pinak]

[Note, the original table – which didn’t make it to the published version of the report – was unreadable in places, which I’ve marked with yellow – Eugen Pinak]

2. Consumption of ordnance during the war - Obtained from the Military Supplies Division.

REMARKS

1.   Year means calendar year.

2.    Unit of measure:               

Ammunitions: One kaisenbun for one division.

Weapons: Equipment for one division.

Trucks: One vehicle.

3.   After the beginning of 1943, consumption by ship sinking began increase gradually.

4.    Numbers include consumption by sinking.

3. Consumption of ammunition, weapons and trucks during the war - Obtained from the General Affairs Section of the Army Ministry (Preliminary Data)

Units of measure:

Ammunition: One kalsenbun for one division.

Weapons: Equipment for one division.

Motor Vehicles: One vehicle.

(Figures include consumption through sinkings, years are calendar years.)

This Information Indicates that total ammunition stocks were not low in 1945 but were nearly at the early 1941 level. Ammunition consumption reached its peak in 1944, when it was twice an large as production in that year. The amount of weapons rose somewhat over the 1941 level, but it did not keep pace with the army which Increased from 2100000 men in 1941 to 5500000 men in 1945. Furthermore, weapon consumption in 1944 was over three times its 1943 level. With trucks there was a continually increasing wastage rate combined with continually decreasing production rate. By 1943 consumption was greater than production and continued so for the rest of the war.

 4. Tonnage of Army supplies shipped from Japan to various areas and sunk en route, 1942-1945 (in 1000’s tons)

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