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The Development of the Army Field Cap (1932-1938)

Article about: The Development of the Army Field Cap (1932-1938) Why a Field Cap? The legacy of WWI put the development of steel helmets and gas masks on the priority list for the Japanese Army, and as bot

  1. #1

    Default The Development of the Army Field Cap (1932-1938)

    The Development of the Army Field Cap (1932-1938)

    Why a Field Cap?

    The legacy of WWI put the development of steel helmets and gas masks on the priority list for the Japanese Army, and as both had to share space on the head of a soldier, they had to be developed in tandem, tested in tandem and issued in tandem. The pair was conceived to be compatible, but this celebrated pair was creating a new conflict elsewhere, a conflict with the uniform visor cap. The helmet and gas mask were conceived as assault gear, and the helmet was only worn by limited people under limited conditions, so the visor cap could initially stay on the head of the soldier most of the time. However, with the introduction of the Star-vent/Cherry blossom helmet as a Provisionary Standard in 1922, the steel helmet gradually spent more time on the soldier’s head and the poor visor cap found itself more and more often looking for a place to stay while the helmet took over. Anyway having to switch back and forth between the helmet and visor cap was becoming a problem. By 1927/28 this conflict could no longer be left alone. They had to find a solution.

    Which shall we fold, the helmet or the cap?

    The army became desperate enough to consider folding, of all things, the steel helmet in 1928. They even patented it. Slightly earlier than that an alternative approach of developing a replacement to the visor cap to be compatible with the helmet was also launched when on September 15, 1927 the Army’s main clothing depot put in a request for a helmet sample “for the purpose of clothing item studies”. At this time, the type 90 helmets were early prototypes at best, so the sample could have only been a cherry blossom helmet, which must have largely sufficed for the purpose of developing a compatible cap to replace the visor cap in the field.

    The folding helmet ended as a curiosity and the Type 90 Steel Helmet was born on 28th October 1930, so now it was the cap that had to yield.

    16th March 1932: Which looks better on us “A or B”?

    By the time that the new type 90 helmets were starting to reach the troops in some quantity, a memo from the clothing office dated March 16th 1932 informed the chief of staff of the Kwantung Army in China that two alternative designs of “prototype combat caps” were to follow in quantities of a thousand pieces each for field assessment.
    An attached memo gave detailed instructions;

    Onsite testing requirements of prototype combat caps (1932)

    1.Purpose of test
    In comparison to the current visor caps these combat caps were prototyped with the aim of being convenient for carrying and if necessary, be used in combination with the steel helmet and gas mask.
    The purpose of this onsite test is to judge its suitability.

    2.Spec outline of the prototypes
    Pure wool as the base material, the star in yellow wool, leather sweatband added and a rear split allowing adjustments from large to small. Sizes in Large, Medium and Small and two alternative external designs Kou (A) and Otsu (B) provided.

    3.Testing Period
    From the arrival of the samples till roughly until the end of October 1932

    4.Reporting of results
    First report: Roughly by end of June you are expected to come back with a value judgment, whether the prototypes are suitable for wear, any improvement suggestions and provide a general report.
    Second report: By end of November, a detailed report is expected.

    Design A was an overseas cap, B was the billed field cap
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  2. #2


    To this request, the Kwantung Army provided their detailed report already on July 12th, 1932

    Test Results of prototype combat caps

    The Kwantung Army


    Response generally favorable after having worn the prototypes here. As to the comparison between A & B, B is the desired choice.


    a) Light weight and pliable feature makes for comfortable wear and convenient for use with steel helmet. As the helmet does not come into direct contact with the head, pain to the head is alleviated and also helps the helmet to be seated better preventing wobble. Headaches caused by long hours of helmet wearing can be prevented. During summer, protects the head from the overheating of the steel helmet.

    b) Even when worn alone without the helmet it assures ease of movement in combat and helps to prevent being easily spotted by the enemy. The light and pliable nature helps to ensure in a march as well as in combat a refreshing feeling both in body and mind. Wide field of vision makes aiming easy. Movement inside trenches, armored trains and barracks is not hindered. Not prone to be blown off in strong winds nor get snagged on branches and knocked off when passing through forests. Soldiers on horseback do not have to worry about interference with the shouldered rifle. One can even lie down wearing it, when bivouacking. Unlike the bright color of the cap band or the shine of the visor from the visor cap there is very little that gives the wearer away to enemy eyes.

    c) It’s refreshing to wear, giving no fatigue and good for hygiene

    d) Small volume and not having to worry about it going out of shape contributes to convenient carrying and storing, as well as facilitating repair and replacement

    3.Comparison between A and B

    B is deemed superior in design for the following reasons

    a) The visor keeps out the glare, running rain or windblown dust from the eyes

    b) The visor is a handy hold for wearing and removing

    c) Can maintain a smarter appearance

    4.Improvement Ideas

    Based on our choice of B improvement suggestions are

    a) To allow for effective ventilation, increase number of grommet vents

    b) The rear split is much too shallow for effective size adjustments. The slit length should be doubled to give a large to small range of adjustment

    c) Use waterproof cloth as core for visor and apply 3 or 4 rows of stitching on obverse and reverse

    d) Size alternatives should be increased to assure best fit, and the small prototype is much too small

    e) The top seam should be hidden by a tape to prevent wrinkles occurring at the top seam

    f) A jute lining will prevent soiling and allow ease of washing

    5.Units represented in the evaluation

    2nd Infantry Division Received 300 of each type
    4th Mixed Brigade Received 200
    8th Mixed Brigade Ditto
    Independent Garrison 50 of each for each battalion

    Field caps in Silk? (1933-1936)

    The caps were extremely well received by the soldiers of the Kwantung Army as can be imagined from their positive reply above. Even before they sent in the report, they placed a request for 28,000 more pieces of the prototype B caps in June 1932 and a further 6500 in September. They were going like hot cakes in Manchuria and Northern China, but the caps still had a very long way to go until they were finally approved as standard in 1938. For one thing, these prototype B caps did not have chin straps nor vent holes yet.

    At this time, the prototype development for the field caps got caught up in a bigger project that involved both the Army and Navy uniforms in a matter of national strategy, which was to employ Japanese silk as material for military uniforms. Wool and cotton were all imports that made Japan vulnerable to trade embargoes and other disruptions of war to international trade. Such situations would also hurt Japan’s silk industry, which was a prime export item. Though silk was more expensive as a material, losing export in war would collapse silk prices and destroy the industry. Therefore if the Army and Navy could make active use of silk, it would make the silk industry less dependent on export and also make Japan more self-sufficient in fabric supply.

    This became a large scale, three year field test for the Army that started in July of 1933 involving a wide range of clothing items with 50% silk content or depending on the item, sometimes even 100% silk. Items tested included visor caps, jackets and pants (both summer and winter), leggings, flight suits, shelter quarters, coats, blankets and even web straps for the canteen, etc. The points that the developers wanted to have evaluated were the following;

    1. Durability
    2. Coolness as summer wear and warmth as winter wear
    3. Effect of rain and snow
    4. Anti-fade performance of dyes
    5. Ease of maintenance
    6. Repair and cleaning costs

    Field cap B was a natural candidate for this project, and joined the silk uniform program a year later in September of 1934 and went through two years of field-testing. 19,500 of these 50% silk prototypes were delivered to units in the continent as well as the Imperial Guards, 1st , 4th, 19th and 20th Infantry Divisions and also to the troops in Taiwan, etc.

    This test overlapped with the continued testing of the Field cap B prototype, and as a result the shipment for the 20th Infantry Division, for instance, that went out in October 1934 had all 70 pieces of large sizes in the silk-mix fabric and 110 of medium and 20 of small sizes in the field cap B configuration. Both designs were similar, but the silk versions had the added improvements of a chin strap and ventilation holes.

    The project report is a few hundred pages long, as many items and divisions were involved in the tests and had to compile detailed reports, but in short, the silk project overall was not greeted with so much enthusiasm mainly, due to the fabric’s vulnerability to abrasions, the nap wearing off quickly, the shrinking and wrinkling, due to rain and washing, etc. However, the initial enthusiasm shown for the new field cap design seemed to carry over into the field evaluations of the field caps using fabrics containing 50% silk.

    Taking the 20th Division’s final report of December 26, 1936 as an example, though many points are a repeat of what was mentioned in the Field cap B report discussed at the beginning of this section, there are some new drawbacks raised that are interesting.

    1. Chin strap. This was mainly added to the silk version to prevent the cap from falling off when wearing the gas mask. However, they found the leather strap abrasive to the throat and suggested replacing it with a rubber strap, which would also prevent the frequent damage to the strap when wearing with a gas mask. The need for strap buttons to be better secured not to come off was pointed out.

    2. Because the field cap lacked the flared crown of the visor cap, rain water ran right into the collar, and similarly the neck was badly exposed to the sun.

    3. In rain, when the hood of the coat was used over it, it restricted movement, particularly when on guard duty.

    4. Fading and nap wear progressed quicker than the visor caps and by the time the test period was over, most caps were no longer within the wearable kit rating.

    5. The visor needed to be bigger and stiffer for the cap to serve as a replacement for the visor cap. That would also work better to keep the sun out of the eyes, and also solve the problem when using the coat hood on a rainy day.

    In the end, they concluded positively that if the chin strap and visor issues were addressed, it would become a more practical and economical alternative than the visor cap.

    In the 20th Infantry Division, the 78 and 79 Infantry Regiments received 600 caps each and the 28 Cavalry Regiment 300 caps and wore them for 2 years as required by the test.

    31st May 1938: Finally a happy threesome, the Helmet, Gasmask and Field cap in harmony

    After 6 long years of searching for a field cap to be compatible with the helmet, they finally sought official approval on 31st May 1938. The occasion was an overall revision of the Army’s Uniform Regulations and the field cap was a small part of a complete new army outfit, which was now sanctioned by the emperor himself with his signature and seal. Here they are below, including the field cap drawing that the Emperor saw and approved at that time. The problem brought up in the field tests of rain running down the neck and the neck being exposed to the sun also got addressed by the introduction of the detachable neck flaps the next day on 1st June, 1938 in army ordinance 31 (the same ordinance that introduced the helmet cover).

    One thing that I need to also clarify at this time is how the field cap was called in Japanese. Initially, when the field cap came out in 1932, the Japanese designation was “Sentou Bo (combat cap戦闘帽)”. This got shortened to “Sen Bo (fighting cap戦帽)” during the field tests, and finally in 1938 it was officially designated “Ryaku Bo(simplified cap略帽)”, because its wear was no longer limited to combat situations. The word Ryaku in Japanese means abbreviated, casual or simplified, which by definition suggests that there was a fuller, formal version, which was the visor cap in this case
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  3. #3


    Regulations regarding wear of the field cap versus the visor cap (1935-1943)

    February 15, 1935: For maneuvers, training and when in the barracks (excepting during guard duty) one may substitute the visor cap with the field cap.

    April 9, 1938: Troops within Manchuria were granted an exception to the regulation above, allowing them wear of the field cap at all times unless otherwise instructed.

    December 22, 1938: Even when Army regulations specify wear of the field cap, troops stationed in barracks within Japan, Korea and Taiwan are to continue wearing the visor cap instead for the time being, unless wear of the helmet required a field cap.

    November 11, 1943: Kempei (MPs) were finally allowed to wear field caps during duty.

    Here is the official spec drawings from 1943 April and an actual example from that year, showing faithful adherence to those specs.
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    Last edited by nick komiya; 10-24-2015 at 03:55 PM.

  4. #4


    Development of the field cap by the Navy (1933-1937)

    As the army developed the helmets and the navy just copied them, the same thing happened with the field caps. Here is a brief description of the meandering path the navy took to its final decision just to copy the army.

    In order to securely seat the helmet upon ones head, the Naval landing forces, the main wearers of helmets in the Navy, had the practice of wearing a hand towel as a headband or simply folding it up and placing it upon the head over which came their helmets. But soon after the Army started testing their field cap designs in the field, in May 1933, the Navy’s Chief Paymaster stationed in Manchuria suggested to the Navy’s War Supplies Office (軍需部) that the Navy should follow suit.

    The Yokosuka War Supplies Office responded in June with five field cap prototypes in Navy blue, which all had visors with the exception of one design. The second round of prototype studies focused on two alternative designs, Type A, a design like a work cap with a flat round top, with visor, and Type B, a brimless overseas cap design with a double fold up at the forehead in a design somewhat similar to the US field caps. This time, a brown summer version was added to the line-up in blue.

    These second generation prototypes were issued for testing to the Navy Gunnery School, the Shanghai Special Landing Forces and to the Naval Base Guard Units. The Gunnery School reported back that the Model with the brim was more suitable, and that they made the troops look a sight sharper than with white towel hand bands when the helmet was off. The same design also found favor with the Landing Forces, but they added that the design worked for winter caps, but for summer cotton or kapok padding was required in the top of the caps, which the Guard Units also supported.

    The third round of prototypes were supplied by the company, Dai Nihon Seibou (Great Japan Hat Manufacturing) in June 1934 and consisted of three alternatives that were given to the Gunnery School for their input.

    Until this time, these caps were called “The Steel Head Armor Underlay Caps鉄兜下帽子” in the Navy, but in September of 1934, for the fourth round of prototypes, the name became “Sentou Bou (Combat Cap)” as initially called in the Army. Once again this resulted in three models, one of which resembled a British Hunting Cap, and one a brimless model. All three sported a Navy anchor in yellow wool in front and were tested by the Landing Forces.

    Ironically all these rounds of prototype studies in the Navy came to naught and when the time came to introduce it as a standard in November of 1937 they had taken over the Army design.

  5. #5
    Rod is offline


    Thank you Nick, wonderful article.

    Regulations re: wearing the field vs visor cap was particularly interesting in light of the many photos of soldiers in visor caps latterly. Good to finally know why and where the various practices were sanctioned.


  6. #6


    There was a question raised about the field cap variation made out of pressed felt, so I will explain what those were. In one word, I should say that it is the field cap version of the so-called Type 3 officer’s sword (or more accurately the 1940 variant of the officer’s sword). It was conceived roughly at the same time for the same reasons as the sword.

    The massive mobilization for the China Incident brought shortages of various items in 1937. As a result of this, the army had to devise fallback plans in the form of substitute materials that could be used. The substitute of uniform wool was felt made out of rabbit hair, which Japan didn’t seem to lack so badly. So they decided to make use of the felt for field caps. These are called Wan-bo (pronounced like “one”) by collectors in Japan as they are shaped like the wooden bowl for soup and is a cap shaped by pressing instead of sewing panels together. These were not prototypes, but a poor man’s version field cap issued to troops within home territory only (including Taiwan and Korea). Everyone else in China, Manchuria, Northern Territories and officer candidates were to be issued the proper standard woolen caps according to Army Ordinance 1389 issued on 1st May 1939. In May 1940 the 6th Tank Regiment and 3rd Antiaircraft Gun Regiment got issued the caps followed in July 1940, by the students at the Kumagaya flight school. On 9th August 1941, Army Ordinance 1740 again confirmed that felt caps were to be issued to home territory troops only, until inventory was exhausted. They likely used up what was left of the felt caps within 1941.
    Last edited by nick komiya; 10-26-2015 at 10:50 PM.

  7. #7


    Superb article Nick, many thanks for taking the time to share it!



  8. #8


    Hi Nick , i just do not know where else such accurate and in-depth information could be gleaned ! On behalf of myself and the forum i offer our thanks , not only for your thread but also the time spent on research and the translation from original period documents !! This information is invaluable .....thanks again .

    I shall now pin this to its deserving position atop the thread list with the other topics you have shared with us

    We are the Pilgrims , master, we shall go
    Always a little further : it may be
    Beyond that last blue mountain barred with snow
    Across that angry or that glimmering sea...

  9. #9


    Thank you for the kind words. German militaria research said good bye to the likes of jet pilot's helmets a long time ago, but in our turf, people still freely spew nonsense. And yet those same people would preach contradictions like "buy the item and not the story". Only hard facts could get us out of this embarassing rut and I am happy to be able to help break that spell we are under.

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