How to date a Frog

[Nick Komiya]

How to date a Frog

No, this is not about dating a wannabe Prince, but about bayonet frogs.

I assume that the evolution of the Japanese bayonet is fairly well covered by other authors, though I can’t vouch for the accuracy of their work. However, when it comes to bayonet frogs, even Japanese books I’ve seen so far only say there were many variations in style and material, as if the IJA was totally confused as to what they wanted.

But the fact is that there was perfect rhyme and reason for those variations, and it is rather the authors that are badly confused. Anyway, what good does it do to have your precious bayonet dated precisely to the year, if you have it mated with a frog that can never be the right prince?

The only way to untangle the chaos created by earlier authors is to start from the origins and track their chronological evolution.

[Nick Komiya]

1898 to 1916

The frog was born in 1898 as “the frog for the bayonet for the Type 30 Infantry Rifle 三十年式歩兵銃々剣々差”. Then as of July 1906, the bayonet became an independent freelancer, now calling itself the “Type 30 Bayonet 三十年式銃剣”, no longer an integral part of the Type 30 rifle specs.

That was because it was also adopted for use on the new Type 38 rifle. Thus the frog finally became “the frog for the Type 30 Bayonet 三十年式銃剣々差” (and the waist belt became “belt for the Type 30 Bayonet”).

Luckily a care manual for the Type 30 and 38 Rifles, printed in February 1899, shows what the frog looked like back then. And shown side by side to the 1899 illustration is an identical 1916 example from my collection.

[Nick Komiya]

1901, the Advent of the Single Belt-loop Frog for Field Gunners


Books may tell you that WW2 frogs were also available in a version that only had one belt loop instead of the “Y” configuration shown above. But actually the one-loop version was already there from the Russo-Japanese War. Those were special versions for field gun personnel.

Artillery personnel ceased to receive rifles in June 1884 and got issued a bayonet-like artillery sword instead. But then, as of 11th November 1898, that sword, too, got abolished and was replaced by the Type 30 bayonet. Thus they, too, initially wore the bayonets in the Y-shaped frogs.

However, a letter from Arisaka, in his capacity as Chairman of the Artillery Commission, addressed to the Minister of the Army, pointed out the problem with this arrangement in a letter dated 26th June 1901.

What he said was that, because of the squatting or sitting posture of the field gun crew 野砲兵, bayonets hung at the standard infantry position, strapped into place by the bayonet support strap of the jacket became a hinderance to operating the guns.

Thus they needed a frog suspended by only one loop, which they could easily slide around the belt to get it out of the way when necessary. They did not have ammo pouches on the belt, so there was ample free space to slide the bayonet around.

A shorter bayonet might have helped as well, but Japanese bayonets were obscenely long for the good reason that, back then, an infantryman had to have enough reach with his bayoneted rifle to ward off an attacking cavalryman on horseback.

Thus an issued weapons list dated 28th July 1902 already included a special bayonet frog for field gun crew.

This single-loop frog continued to be used into WW2 and its use spread to cavalry, Flak and motorized transport drivers, etc. This was merely meant to be a variation of the Y-shaped version, so changes made to the standard Y-frogs were also applied to these as well. As such, the following changes happening to the Y-model in 1917 got applied to the field gunner's model as of 18th May 1917.

[Nick Komiya]

1917 to 1931 (?)

On 21st November 1916, army developers submitted for approval by the Minister of the Army, a design improvement to the frog that solved some inherent problems.

What they wanted to fix were three weak points.

The sewing at the bottom part of the two belt loops and at the top part of the pocket, holding the bayonet scabbard soon became undone, and a crack tended to develop at the center of the frog.

The new design to deal with these problems was approved on 22nd February 1917 and consisted of:

(1) widening the space for the belt to slide through

(2) adding a rivet to the top edge of the pocket, as well as making the pocket leather thicker

(3) omitting the sewing around the hole, as well as the vertical seam above it, as these seams caused cracks to develop.

As already mentioned, these changes were made to the field gunner versions, too.

[Nick Komiya]

1932 (?) to 1939


The next change made to the bayonet frogs was to enlarge the brass buckle attached to the scabbard hold-down strap. The width of the buckle remained unchanged at 13 mm, but the frame length got stretched vertically to 24 mm from the previous 15 mm in order to make it easier to pass the thin strap through the buckle.

What was previously almost a square buckle now became an oblong buckle.

Precisely when this buckle swap was done is not known to me at this time. But as events up until 1928 are well documented, I assume it to be a later development.

A larger buckle I associate with functionality in cold weather, the kind experienced in the Manchurian Incident of 1931.

Another reason I guess it to be around 1932 comes from a report made after the grueling Siberian Intervention Expedition ending in 1922. The report said that the Type 30 bayonet scabbard needed to become easier for the men to take apart in the field, as rain and snow got inside, often requiring dismantling for draining and drying. This would have required the scabbard to be slid out of the frog and doing that often in the cold with freezing hands would have naturally benefited from a larger buckle.

If collectors have dated frogs with the earlier small brass buckle, it would serve the collector community to know the dates, so we can get a better fix on when the buckle enlargement happened.

[Nick Komiya]

1940 March and May changes


The next change to come was to comply with the material substituting guidelines issued by the army in order to conserve brass. Thus the brass buckle and rivets got switched to steel as of 23rd March 1940.

This was soon followed by another minor improvement on 27th May 1940, at which time, the thin scabbard hold-down strap was made 10 mm longer and the number of holes for the buckle’s pin got increased to three holes from the previous 2 holes. The diameter of the steel disc used in conjunction with the rivet was also increased slightly to prevent the rivet from sinking into the frog.

These changes were also applied to the field gunner versions, so clearly there were two separate frog designs in use until May 1940.

It was also at this time that the cross-guard of the bayonet lost the hook and became straight, so you can say that bayonets with a straight guard should have a frog set up with 3 buckle holes instead of 2.

[Nick Komiya]

The Rubberized Canvass Substitutes


Immediately following the China Incident of 1937, intensive studies were done to devise countermeasures for the expected severe material shortages to come. One such expected crunch was leather supply from the USA. So already in March 1938, plans were signed off to switch leather items to rubberized canvass. At that time, bayonet frogs were also planned to switch ASAP.

When exactly they were able to start actual production of these rubberized canvass versions is not clear, but a production report issued in March 1939 by the army’s largest supplier of leather equipment, Sanyo Leather Company had them churning out as many as 100 thousand pieces of leather frogs that year, and they were not yet complaining about any material shortages. So most likely they started only in 1940.

Either way, an army suppliers list of January 1941 had as many as 6 manufacturers actively making ammo pouches in that material, so they were at least well in supply within 1940.

It appears that those 1940 rubberized versions were initially in the same “Y” design as the leather versions. They had also switched the thin scabbard hold-down strap to rubberized canvass. However, they wore out too easily, so on 29th March 1941, the army decided to go back to using leather for that one strap. The report also mentions that rubberized canvass or art bark substitutes for leather did not stand up well in front line usage, due to poor durability. It recommended to issue them to training and rear line troops and prioritize frontline troops for proper leather versions.

Now at this point, the document trail vanishes, leaving one question I cannot answer. Collectors would know that the majority of the rubberized canvass frogs found today are not in the Y-configuration, but with only one wide belt loop with a hole in it that can take the tunic’s bayonet suspension strap.

To me, this is a brilliant case of design Kaizen that unified two previously different frog designs into one. Field gunners and infantrymen should have been equally happy with this design.

When was this two-in-one design launched? The example recently posted on this forum was dated 1944, but aren’t there earlier dated ones? I have one with the brass buckle on a two-hole, hold-down leather strap, but the markings that should have been on the rear have disappeared. The leather strap makes it a post March ‘41 production, but using a two-hole pre-May ‘40 strap, combined with a pre-March ’40 buckle.

Use of these pre-1940 parts strongly suggest that the two-in-one configuration of rubberized frog was already in production in early 1941. These are actually far from being last ditch, as collectors like to call them.

Did a leather version of this design exist? Again any examples in collections would be interesting to see. However, the distinction of “Bayonet Frog for Field Gunners” will remain until the end of the war, when arsenal inventory to be surrendered mentions them in stock.

[Nick Komiya]

Markings

Frogs seem notorious for losing their markings, leading one author to even claim they were rarely marked. But that is nonsense, as markings were mandatory, and merely faded away, because of frequent oiling and polishing by the soldiers. Markings also seemed frequently to be applied by rubber stamps instead of indenting the leather surface, which would explain the lack thereof in surviving examples in collections.

Marking regulations for Weapons as issued on 1st July 1924 said leather weapons (frogs were categorized as a leather class 2 weapon, being part of the bayonet spec) were to have 3 stamps.

(1) Year & Month of manufacture or year only
(2) Acceptance Stamp
(3) Producer or Arsenal ID.

Location of the markings depended on the construction. Straps with metal fittings at the end, like D rings, would have the stamps on the rear, close to the seam holding the metal. Those with seams close to the center were to have stamps on the back located close to the center seam. Other straps were stamped at the rear end or at center. Lidded pouches were stamped on the underside of the lid. Accordingly, frogs were stamped at the rear, near the seam.

[Nick Komiya]

Well, a few questions still remain, but that should clear things up for a lot of collectors.

Regarding spec introductions, of course, stock of old parts were used up before switching entirely to newly adopted specs, so in real life, overlaps would have occurred.

I'm too short on dated examples, so any photo contributions of dated examples are welcome.

However, as usual, I will be adding new information to this thread as I come across them, so I would appreciate it, if you do not litter this thread with questions and such that can be done as a separate thread.

[Nick Komiya]

Here's already an update on the 2-in-1 design. What I earlier described as a leather-saving version with an extra seam is actually a transitional model towards the 2-in-1 design, a convertible design!

The one on the left below is an older design and the right one is the transitional model. See how the red-boxed bottom section of the transitional model is identical to the field gunner version in post 3. All you did was change the top leather that sandwiched this bottom piece to switch between the two models. In order to achieve this, they totally changed the layering arrangement of the leather as apparent from the side views.