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The Evolution of the Japanese Army Steel Helmet (1918-1945) Revised and Expanded Version

Article about: The Evolution of the Japanese Army Steel Helmet (1918-1945) Prolog During the Russo-Japanese War, the army received a letter dated 28th April 1905 from a private inventor, who had the idea t

  1. #11


    The name “Testu Kabuto” (steel head armor鉄兜) used since the 1918 model, was changed to simply “Kabuto兜” by dropping the reference to steel. It gives it an archaic ring as the new name harks directly back to the head armor of Samurai days. It appears that even at the risk of sounding low-tech and primitive, the army wanted to disassociate itself from the M18 fiasco even in name, a standard marketing ploy these days to wipe the slate clean for a model that was a dismal failure in a previous life under a different name. Anyway, this extraordinary name change was seen as important enough to bring it to the attention of the Minister of the Army, so it cannot be anything else than an indirect reference to something they all wanted to put completely behind them. As if to confirm this, the designation promptly goes back to “Tetsu-Kabuto” as they later switch again to the Type 90 helmet.

    Provisional Type = Equipment on Probation

    The Type approval of the “Provisional Standard Kabuto仮制式兜” (This is the official designation for the star-vent/cherry blossom helmet) was finally granted on June 15th, 1922, marking this as the date of introduction of this second generation Army helmet.

    The term “Provisional Standard” perhaps requires some explanation. The type approval for the Army’s standardization process for weapons normally starts by introducing something as a provisional standard, and once it proves satisfactory in the field, another application is made to remove the provisional title.

    For instance, when the Nambu 14 received its type approval, it was as the “Provisional Standard Type 14 Pistol”. In order to drop the provisional title the hardware needed to build up a convincing track record. For example, some communication equipment that became provisional standard in May 1934 finally was approved as standard in May 1939, and the document cites its service in the front line in China and that it has reliably proven its function. Actually the army’s weapons code allows a maximum of two years as a rule of thumb for this probationary period, but many items stayed in this state much longer. And like this 1922 model helmet, some items never made it to become officially type approved.

    As the first Army helmet, the Siberian Incident Model, was not acknowledged with any official designation (it was not even a Provisionary Standard), there was no need to name the Cherry Blossom helmet as “Provisional Standard Kabuto Type 82 (imperial year 2,582)” to distinguish between them. The army treated the 1922 helmet as if no helmet ever existed before it.

    Initial Version of the 1922 Model = “Star-Vent“ Model`

    Unfortunately, the helmet drawing which was originally attached to the March 31st document above has been lost to time. (There is even a slight chance that it is still in the US National Archives, as these documents were all long in the possession of the Americans after WW2 and only returned to Japan after they had finished with them) However, had the drawing still been there, I am now quite certain it would have shown the so-called star-vent helmet without any insignia attached to the front. This type had a series of small salt-shaker like vent holes on top that collectively form a star-shape, thus earning the nickname “Star-vent” among collectors.
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    Last edited by nick komiya; 10-23-2015 at 11:32 PM.

  2. #12


    The photo below is the reason I believe this to be the initial configuration of the 1922 helmet. The photo is dated May 1928. The occasion was the army's third expedition to China's Shandong Province. As a result of WW1, Japan was given former German possessions by the Treaty of Versailles, but this met great resistance in China, giving rise to massacres of Japanese civilians in the area. The photo is regarded by many as showing the first combat use of a steel helmet by the Japanese army. Note that the photo does not show any cherry blossom vent covers at the top and this is already 6 years after the introduction of the 1922 provisionary standard helmet. Everyone wearing a star-vent helmet 6 years after the introduction of the Provisional Standard Helmet can only mean that for a considerable length of time after 1922, the helmet was manufactured in this configuration. At the same time this also serves as proof that the star-vent helmet is not the M18 as many collectors had believed, as they surely would not be wearing obsolete 1918 helmets when they had a full 6 years to switch to the 1922 model.
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  3. #13


    So the star-vent helmet in the photos above is the initial version of the 1922 Provisional Standard Helmet. The omission of insignia is quite natural due to its status as a weapon rather than a uniform item, and was only added later as an afterthought. The status of weapon meant it was not issued to the soldier for constant wear, but rented out to him only when protective gear was called for, for instance, assaulting an enemy position. The helmet only became a uniform item in 1932 with the type 90 helmet.

    Unfortunately there are no documents showing when it was that the star-vent helmets got cherry blossom vent caps on top, but one can assume it had to do with the short comings of the star-vent design letting too much water in during rain. Shown below is what collectors call the cherry blossom helmet, which was the second configuration for the 1922 model.
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  4. #14


    After 8 years of service when the Type 90 helmet was officially adopted as a full- fledged Standard on 28th October 1930, the introduction document added at last “ Thus the Provisional Standard Kabuto as introduced on 15th June 1922 in Army Ordinance 2661 is hereby now void and discontinued” .

    However, during 1931, well after the Type 90 had been adopted, they still produced 3,250 cherry blossom helmets concurrently alongside the Type 90s. This was obviously because they couldn’t crank out enough Type 90s at the start. The Type 90s were predominantly manufactured by Kobe Steel at that time, so anything that the Tokyo Arsenal could make contributed directly to ease the shortage. Such late cherry blossom helmets represent a third and last variant configuration of the 1922 design by stealing features from the type 90 helmets, namely the 3-point chinstrap suspension system (versus the 4-point system of the star vented helmets and earlier cherry-blossomed helmets) and the four ventilation holes on top. This last version has also been observed with a canvas liner instead of leather, but how common this practice was at that time is not known.
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  5. #15


    July 1932: Phasing out of the cherry blossom model

    Finally, by summer of 1932, the supply of the new type 90 helmets for the Manchurian Incident had stabilized, and Army Manchuria Regular Ordinance 1769(陸満普第1769), dated July 22nd 1932 announced that all old type helmets in the Manchurian “Incident Theater of operations (Manchuria, China and Korea)” were to be exchanged with the new Type 90 helmet stocks from the Army Depot and costs charged to the Manchurian Incident budget. With this order, the old helmets ended their front-line duty in the Army, but continued to serve their new, but second hand owner, the Navy.

    January 1932: Second-Hand Life as the Navy cherry blossom helmet

    I noticed that there are some collectors that believe that navy versions of the cherry blossom helmet were produced alongside the army ones. No, it did not happen like that. The navy only got their cherry blossom helmets after the army had already switched to Type 90s. In fact, what the navy got were only old second-hand army helmets, which got the insignia switched to navy ones. Here is how it happened.
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  6. #16


    At the end of January 1932, after the Army had already launched the type 90 helmet and rendered the cherry blossom model obsolete, the Shanghai Incident broke out, requiring the Navy to bolster its Naval Landing Force presence in the city by 7,000 troops from Japan. However, this suddenly caused a shortage of weapons for the Navy troops, who sent an urgent call of help to the Army arsenal. The Army responded in end of February by selling the Navy 2,000 Type 38 rifles with Type 30 bayonets, 500 Nambu 14 pistols, 150 Type11 light Machine guns, etc. This supply included the sale of 1,700 cherry blossom helmets, which will be known within the Navy as the “Model 2” helmet. These helmets joined the “Model 1” helmets that the Shanghai Special Naval Landing Forces were initially equipped with in 1929 to create the chaotic mixture of helmets seen worn in period photos from the incident.
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  7. #17


    The Development of the Type 90 helmet

    January 10, 1927: Launch of Type 90 Research & Development

    The development project for the Type 90 helmet was launched within the Army’s Technical Headquarters on January 10, 1927.

    The cherry blossom helmet, which had been adopted as a provisional standard in June 1922 had revealed some drawbacks that they sought to address. It had, according to the official Type 90 development report, a “complex shape not easy to produce, was heavy and inconvenient for use, particularly when shooting in a prone position, as the rear of the helmet got caught against the backpack, hindering movement during combat”. It is interesting that the developers of the Type 90 regarded the cherry blossom helmet as heavy, as in fact, they are usually lighter than the Type 90. Perhaps they took the late model cherry blossom helmet as a baseline for comparison. That model incorporated many features developed for the Type 90 helmet, which probably included thicker gauged steel, making it heavier than a Type 90. Actual weights of examples in my collection are as follows.

    Type 90 helmet in small size---- 1133 grams (0.95 kg according to the 1930 specs)
    Type 90 helmet in large size-----1181 grams (1 kg according to the 1930 specs)
    1922 Star vent helmet------------ 834 grams
    1922 Cherry blossom------------- 941 grams

    Establishing Development Objectives

    They set up the following four objectives as goals in the study.

    1. A shape that is easy to manufacture.
    2. By keeping protective qualities to a certain limit, minimize weight
    3. Attributes of economy that allow self-sufficiency of production
    4. Use of a metal that satisfies the above three conditions
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  8. #18


    1927 April--Benchmarking against foreign examples

    In order to set up a benchmark study, the Army started collecting helmets of various western armies from April 1927. Prototyping studies were launched at the arsenal, and they also got hold of an example of the helmet produced by the Army on the occasion of the “Siberian Incident” of 1918 for comparison.

    The foreign helmets used for bench-marking were German, Swedish, Swiss, Danish, Dutch, British, French and American. (Though, the official report claims that comparison studies with foreign helmets started in 1927, the Army medical school had actually been collecting foreign helmets at least for the last 3 years, as they wrote to the Army arsenal in April 1924 for a sample of the latest Japanese version to add to their comparative studies.)
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  9. #19


    1927-1929: Development progress

    In May 1927, a joint study was launched with the arsenal to develop a suitable alloy, and in June, a rifle modified to shoot shrapnel shell pellets at variable velocities was completed along with a designated firing range for testing the helmets.

    The foreign helmets that started to arrive and the prototypes from the arsenal numbered 160 in total, and tests on these helmets were conducted between November 1927 and January 1928 at the range, where the deflection characteristics, alloy makeup, weights, thickness, shape, etc of the samples were studied and compared in detail.

    And in February 1928, anti-shrapnel testing was done at the Tomitsu Range located at the tip of a cape that juts out into Tokyo Bay. There the helmets were exposed to fire by real shrapnel rounds from a Type38 75mm Field Gun, Type 10 grenades and high explosive rounds fired from the Type 38 Field Gun.

    Based on these test results, a finalized design was devised, and in October of 1928 an order was placed with the arsenal for a large and small size. These preproduction samples were delivered in March of 1929 and tested to verify that their weight, deflection characteristics, shape and material all met the initial objectives laid out.

    1929-1930: Field Evaluation and Improvements

    From July 1929, field evaluations were carried out to check wear comfort and portability. For this, the Army Infantry, Cavalry, Field Artillery and Heavy Artillery, as well as Field Engineer Schools were requested to participate and provide improvement suggestions.

    The prototype helmets supplied to the schools were different from the finalized Type 90s in two major respects. They had no ventilation holes on top and had a different chinstrap system.

    Ventilation holes were added to the Type 90 in response to requests from the Cavalry and Field Artillery Schools who wanted “grommet vents like in their visor caps”.

    The chinstrap system was different from the final system in that it was shorter, had a metal buckle closure and was a one-piece construction rather than the two-piece system finally employed in the Type 90.

    At 65 centimeters in length, the chin strap was found to be too short for wearing the helmet in conjunction with a gas mask and the Cavalry School suggested extending the length to 70 centimeters.

    The buckle closure employed was deemed cumbersome by the infantry and engineers, who suggested a simpler open-faced buckle design like that of the waist belt. The Cavalry as well as the Heavy artillery Schools further suggested using rubber straps as per gas masks, particularly for the back strap, and it was the Heavy Artillery School that suggested, making the front and rear straps into two separate straps that could be tied under the chin.

    The idea of rubber straps was not incorporated, because of the poor durability that rubber straps would have had, but the straps were lengthened, made into two separate straps and a buckle system was discarded altogether in favor of a simple tie string arrangement under the chin.

    The infantry school still complained that, though better than the cherry blossom helmet, the rear of the helmet still came into contact with the backpack, but developers ruled against trimming the rear any further and compromising protection.

    Regarding the carry method when not worn, the infantry and engineers suggested attaching to the back pack flap, while the Heavy Artillery School came up with the idea of hanging it in front, on the left chest, for which they requested a slit (5mm by 25mm) to be added to the bottom of the rear skirt of the helmet. They also preferred to have the helmet’s front plane to drop straight down in a perpendicular way rather than slop forward, but both of these shell changes were rejected, due to poor deflection, strength and manufacturing considerations. The following illustrated report summarizes the various suggestions raised by the troops. Unfortunately the photos lack the quality for us to be able to see how the unique chinstrap system worked, but it may have been the friction buckle system that soon got employed in army bread bags, if we may be allowed to speculate.
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  10. #20


    March 1930: Official introduction

    After incorporating these improvement suggestions, the helmet was deemed ready for adoption by the Army. On March 31st, 1930, The Army Technical Headquarters released the documentation, titled “Type approval of Close Combat Equipment, Type 90 Tetsu-Kabuto” in the name of its chief, Toyohiko Yoshida, requesting type approval by the Minister of the Army, Kazunari Ugaki. This document got its final stamp of approval on October 28, 1930, and the Star-vent/Cherry blossom design introduced in 1922 was finally superseded and discontinued. The Army thought it finally got the right helmet after 12 years since its first try back in 1918, and the Type 90 became the first “Standard Type” helmet, no longer a “Provisional Standard”.
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