The fighting in the Pacific during the Second World War was brutal. As supply and manpower issues began to take their toll, Japanese military leaders began to look at other options for inflicting casualties on allied forces in a bid to slow their advance toward Tokyo. The Japanese had found that land mines and booby traps were especially deadly within the dense Jungles of the South Pacific and buried amongst the rubble of destroyed cities in the Philippines.
As the allies advanced, the Japanese military began to rapidly increase their already heavy use of land mines and booby traps. The need for increased production, and the lack of some war materials forced the Japanese to take advantage of materials that were generally uncommon for mines and explosives during WWII. The Japanese had already had a large, and long-established pottery industry. These pottery shops were put to work creating pottery and ceramic casings for explosives, mines, and grenades such as the Type 4 ceramic grenade. Land mines were also mass produced by independent shops; the Type 3 ceramic land mine is one such example.
American and Allied forces understood that as the fighting crept closer to Japan, the Japanese would increase the number and type of mines and explosives used. If an invasion of Japan were to occur, and it was indeed being planned, allied forces could expect to encounter land mines, hand grenades, and other ordnance by the millions. There was a great need to expand and train up the US Army Engineer Corps, so that these devices could be dealt with. US Army combat engineers would be expected to clear the majority of mines and ordnance from the battlefield.
In June of 1945, the American War Department released training kits to aid in the training of engineers bound for the Pacific. These kits, formally knowns as, Mine, Training Aid Set No. 2, Japanese, were an assortment of the most commonly encountered Japanese mines. The set also includes a Japanese Type 97 hand grenade. While not a mine itself, they were commonly encountered as expedient mines and often used in booby traps.
The components of the kit are not actual Japanese ordnance, instead they were manufactured in the US to realistically replicate their Japanese counterparts. Because of this, many components don’t fully disassemble or come apart as the true Japanese pieces do. Only the parts that would be disassembled in the field by engineers to make items safe are able to be broken down. Despite that limitation, most parts of these kits do disassemble to a certain degree and there is much to be gained from what can be taken apart.
The entire package of the training kit includes a wooden storage crate measuring 39 inches long, 13 inches wide, and 6 inches tall. The lid features two hinges on the rear, and two closing hasps on the front. Carry handles are carved into either end of the crate for carry. These boxes can be found in varying degrees of shade, from almost pristine examples in bright unfinished wood, to dark and stained examples. The lid features in bold black characters, Mine, Training Set No. 2, Japanese. The front of the crate is marked with a large red engineer castle and nomenclature information in black paint.
The inner portion of the lid also bears a small poster that gives practical translations of the Japanese characters found on the different types of ordnance, as well as a visual breakdown of what should be included in the kit with all the different components called out by name. Altogether, the entire set weighs approximately 41 pounds.
The interior has spaces for each of the included pieces of the kit, with two spaces not being used. A complete Japanese mine training set consists of:
1 Type 93 anti-tank/anti-personnel land mine.
1 Type 93 mine fuze.
2 Type 93 drag ropes.
1 Type 97 hand grenade.
1 Type 3 ceramic land mine.
1 Type 3 mine fuze.
1 Type 99 anti-tank magnetic mine.
1 Yardstick anti-tank mine.
4 yardstick anti-tank mine fuzes.
1 manual (TB ENG 79).
Type 93 anti-tank/anti-personnel land mine.
The Type 93 is a small round landmine made of thin sheet steel and painted dark olive drab. It measures 6.5 inches in diameter, 1.5 inches tall without the brass pressure plug installed, and 1 7/8 inches tall with the plug installed. The sides are corrugated and have two D-shaped rings attached to each side by a steel strap. The D-rings are for the attachment of drag ropes on either side. The drag ropes measure approximately 18 inches in length and can be used to drag the mine along with you while prone, to sling the mine under a tank, or as carry handles. A string can also be tied to the D-rings so that the mine can be pulled into a road, and under a tank’s tracks. The Type 93 also features a leather or rubber washer, and a brass safety ring marked with the Japanese Kanji character 安 (Anzen) meaning, “Safe”.
Normally, the Type 93 is employed as an anti-tank mine, and the fuze is activated by the use of a shear wire. TB ENG 79 states that, “250-pound pressure on the pressure plug will fire the mine. The pressure plug depresses the striker pin which cuts the shear pin. Spring drives striker pin downward, firing percussion cap-detonator-booster-main charge”. According to US documents from the era, a 25-pound shear wire was used in the mine for anti-personnel use.
The actual Type 93 weighs 3 pounds, two of which are picric acid explosive. Due to the mines’ small size, the ropes were often used to fasten multiple mines together in a stack, typically 3, thus amplifying the explosive force. The mines provided in the training kit are hollow, and weigh approximately 1 pound, but a hole and plug are provided on the bottom of the mine so that it can be filled with earth or sand to simulate the real mines weight. Real Type 93 mines do not have this filling hole. This is the sure-fire way to differentiate between a US made training mine, and a real Japanese Type 93 anti-tank mine.
Type 97 hand grenade
While the Type 97 hand grenade isn’t a mine in its own right. The Type 97 can, and was often used as, an improvised land mine. It could be placed inverted inside a tube and hung above a large rock and attached to a tripwire. When the wire is pulled, the grenade falls fuse first into the rock, and the time train is activated. TB ENG 79 also states that, “The grenade has a delay fuze, but it can be removed and the detonator taped in the normal position of the delay train. With this change, the grenade fires immediately upon pressing the cap”. Improved mines using the Type 97 grenade were encountered bured in the ground and fastened within a wooden block filled with more explosive.
The Type 97 grenades provided in the training kit are very rough cast steel and painted black. The top cap is permanently affixed and painted a dark maroon color. The base of the grenade is affixed with the correct paper label and marked with Japanese Kanji characters meaning, “Delay, 4-5 seconds time”. The fuze train is solid turned brass, and only the end cap, safety pin, striker, and spring are removeable. These grenades are often missing from the training kits.
Type 3 ceramic land mine
The Type 3 is a mass-produced anti-tank/anti-personnel land mine made of terracotta or ceramic pottery. There are two variants of this mine called out in the manual, the first is 10.5 inches in diameter and filled with 6.5 pounds of explosive. The second type is smaller, measuring 8.5 inches in diameter, and filled with 4.5 pounds of explosive. The type of explosive used is not mentioned in TB ENG 79, but other references say that it was filled with Type 88 explosive.
The mine provided in the kit is closer to the smaller type, and measures 8 7/8th inches in diameter, 3 7/8ths inches tall with a slightly domed top and painted a dark earth brown. The center of the mine has a taper hole for holding a rubber plug that allows the fuze to be inserted. This plug also serves to keep the mine watertight once buried.
The fuze for the Type 3 mine is made of black Bakelite and is quite simple, yet ingenious in its design. Assembled with its detonator, it measures 3 inches tall and 1 3/16ths inches in diameter. The fuze can be activated by pressure, or by trip wire. The fuze is made up of several different components, The upper and lower bodies, plunger, plunger spring, striker, and striker spring, plus a safety pin, and a forked firing pin. The safety pin is attached to a tan tag that reads, “Safety pin”. The forked firing pin has a red tag that states, “DO NOT PULL, DANGER”.
The striker is held up by a forked firing pin that slips around a groove machined into the striker’s head. This pin has a center tab as is held in place by the safety pin when installed. The safety pin does not allow the forked pin to move rearward. When used as a pressure device, force is applied to the top of the plunger, which pushes the striker past the forked pin. The striker is then shot downward by the striker pin and the mine detonates. The Type 3 can also be used as tripwire. Simply tie a cord or wire to the forked pin. When pulled, this wire pulls the forked pin out, and releases the striker.
These mines contain very little metallic parts and can be difficult to pick up with a mine detector. They were often employed in roads, airfields, and trails. Japanese doctrine also dictated that rows of mines should be used around defensive structures like bunkers.
Type 99 anti-tank magnetic mine
The Type 99 mine is one of the most unique pieces of Japanese ordnance. While technically a mine, it functions in a similar manner to that of the Japanese Type 97 hand grenade. The mine body measures 4.75 inches across, or 6.75 inches from magnet to magnet and is covered in khaki canvas with a triple snap closure at its bottom. There are 4 magnets attached to the canvas case which allow the mine to be stuck onto metal objects such as tanks and bunker doors. These mines are filled with 1.5 pounds of TNT explosive cut into several blocks. TB ENG 79 states that, “One mine will perforate ¾ inch of armor plate; two mines used together will perforate 1 ¼ inch of armor plate”.
The fuze and detonator are somewhat similar to the Type 97 grenade. The head of the fuze is a spring-loaded cap which fits over a brass fuze housing. The cap is held upward by spring tension, and screw retains the cap on the fuse. The rest of the fuze system is made up of a delay element, providing 4 to 5 seconds of time delay, and a booster assembly that screws on to the end of the delay. The entire fuze element of the Type 99 magnetic mine measures 5 ¼ inches in length.
The Type 99 mine provided in the training kit varies slightly from its live counterpart. The explosive blocks are replaced with 3 wooden blocks to simulate the weight and feel of the real mine, and the magnets are simply stand ins, and are not actually magnetic (kind of a let down if you ask me). The fuze functions in practice similar to the real fuze, however the booster and detonator are solid turned brass, but they do disassemble from each other.
The Type 99 mine could also be used in an anti-personnel manner, and the manual gives one such example. The mine is placed into a hole with the fuze slightly above the ground surface. A board is then placed over the fuze, and the safety pin is removed. Once foot pressure is allied, the fuze will activate, and the mine will detonate.
Example of the Type 99 mine employed as a land mine and its carry case to the far right.
Yardstick anti-tank mine
The yardstick mine, referred to in some publications as the bar mine, is a Japanese anti-tank mine that was usually buried in landing strips, and along roads. The yardstick mine measures 36 inches long, 3 3/8ths inches wide, and 1 3/8ths inches thick. The outer casing is made of thin sheet steel painted olive drab and formed into an oval shaped sleeve. Two end caps are held onto either end with slot head screws. One end is simply a blank end cap, while the other end is used for loading the mine with
explosives and contains the safety wire and its retaining clip. There are Japanese characters in red paint on either side of the mine. One side states, “Fuze, top side of mine”. The other side reads, “fuze bottom side of mine”. The explosive blocks and fuzes must be inserted into the sleeve in the correct orientation, or else the safety wire will not feed through the fuzes.
The mines total weight when fuzed is 10 ½ pounds, six of which are picric acid explosive. These mines are fuzed by four pressure activated fuzes that contain the plunger, striker, and booster in a single assembly. According to TB ENG 79, it takes at least 335 pounds of downward pressure on a fuze in order to detonate the mine. These mines were often used in conjunction with aerial bombs. Newsreel footage taken on the island of Iwo Jima has been found showing a Marine engineer clearing a yardstick mine placed on top of what appears to be a Japanese 250kg bomb. The footage also shows the damage these devices caused to Sherman tanks, and how these mines were disarmed in the field using a Ka-Bar combat knife. View it for yourself at https://www.youtube.com/watch?v=6JrMHVP9nYY
The yardstick mine included in the mine training kit is incredibly well detailed. The red Japanese characters are represented well on either side, and the mine also includes 8 plaster of Paris blocks painted yellow to represent the picric acid explosive blocks. The fuzes are solid metal, and do not have any moving parts and cannot be disassembled, but they can be inserted into the blocks and the whole assembly can be loaded into the mine’s body. The safety wire is also dutifully represented, and can be fed through the fuzes and secured in the mine’s end cap. Be careful, the plaster of Paris blocks can be fragile, as I discovered.
In the field, these mines would be prepared with explosive blocks, fuzes, and safety wire installed. This is the safe configuration of carrying and transporting the mine. When ready for use, a shallow pit would be dug, and the mine placed inside with the fuze tops facing upward. The safety wire would then be removed, arming the mine. Cover with a thin layer of soil for camouflage, and the mine is ready to catch unsuspecting tanks and vehicles.
Manual (TB ENG 79)
The TB ENG 79 manual that is included with the kit is short, but a wealth of information nonetheless. Each of the different pieces of the kit are discussed in detail. The manual states that it, “covers use, recognition, functioning, and disposal of common Japanese mines”. Not only does the manual give a thorough breakdown of the kit, but also includes an authorized distribution list that details who should receive the kits.
How many kits were made?
Over the past several decades, collectors have tallied these numbers and determined that 592 of these kits were produced. Considering the kits are relatively rare, this number seems logical; however, I believe these figures are often misunderstood, and the actual number of kits produced is likely closer to 750. The kits listed at the bottom of the distribution list under ASFTC (Army Service Forces Training Center) are well-documented and specify how many kits each engineer training center would receive, totaling 525 kits. Confusion arises when collectors also add the number of kits in the upper portion of the distribution list.
The upper distribution list specifies how many kits would be issued to certain units but not the number of units. For example, the first item in the upper section is "Sch; AGF Repl Depot…RTC" (School, Army Ground Forces Replacement Depot…Replacement Training Center), earmarked to receive 60 kits. There were two replacement training centers, one at Ft. Meade, Maryland, and the other at Ft. Ord, California. This means each RTC would receive 60 kits, totaling 120.
Following the RTCs, the manual states that each division's engineer battalion would receive training kits, divided into 3 kits per company. An infantry division typically has one engineer battalion comprised of four to six engineer companies. Each company in the battalion would receive 3 kits, meaning an engineer battalion would receive a total of 18 kits.
To provide a better perspective, there were approximately 20 army divisions that fought in the Pacific. Each would have an engineer battalion with at least 4 companies, leading to at least 88 engineer companies in the Pacific theater, each receiving 3 kits for a total of 264 mine training sets. Adding about half a dozen independent engineer battalions and companies assigned to other units, you can probably add another 30 kits.
In total, we can estimate the number of training kits assigned. Approximately 300 kits were distributed across all the divisions, plus the 525 kits assigned to training schools stateside, and the 120 kits assigned to each RTC. In theory, about 950 kits could have been called for, with additional kits issued to units redeployed from Europe to the Pacific.
In reality, I believe the actual number of kits produced is closer to 750. Training schools and RTCs would have undoubtedly received them first, with line units receiving them later. These kits were introduced in June 1945, and the war ended two months later.
Overall, these kits likely saw very little use, given the war ended shortly after their introduction. Orders for the kits were probably stopped in August 1945, and the issued kits were most likely put into storage. Years after the war, these kits were sold off to the general public as military surplus, many of them never being used. Complete examples can be found but are increasingly difficult to locate. Common missing elements from these training kits are the Type 97 grenade and the TB ENG 79 manual, along with smaller items like mine fuzes.
Are they authentic Japanese items, or US made training aids?
Occasionally, individual components appear in collections or for sale online. Even the empty crates have been encountered. Unfortunately, many of the items in the training kits have been sold as Japanese originals. There are a few ways to determine the difference between original Japanese items, and their US made counterparts.
Type 93 mine
The Type 93 mines included in the US kit have a filling hole and plug on the underside of the mine, Japanese originals do not have this hole. Also, the two halves of original Japanese mines can be unscrewed from each other for filling with explosive. On US made mines, the two halves are tack welded together at the seam, and do not come apart.
Type 97 grenade
There are several features on the US made Type 97 grenades that you can use to determine that it’s from a US training kit. First, the US made grenades are much more roughly cast than the real Japanese grenades, with very offset cast seams. Second, the top cap is painted a darker maroon color compared to the brighter red of Japanese grenades, and the cap is permanently attached to the grenade body. Third, the fuzes are solid turned brass and only the top striker and cap portion of the fuze can be disassembled. Real Japanese fuzes are also marked with Japanese characters and production dates, US made examples are not.
Type 3 land mine
The US made Type 3 ceramic mines can be extremely difficult to tell apart from a true Japanese example. First, original Japanese mines tend to be a lighter shade of earth brown then the US mines and can have a slight gloss sheen to them. Second, Japanese ceramic mines were internally coated with varnish to aid in waterproofing the mine, US made ceramic mines do not have this internal coating.
Type 3 mine fuze
The US made Type 3 mine fuze is commonly encountered in collectors’ circles and the real Japanese examples are incredibly rare. The most sure-fire way to tell a US example from a Japanese one is by examining the bottom portion of the fuze. US made examples lack the firing pin and its recess inside the bottom portion of the fuze. On US Type 3 mine fuzes, the detonators are not removable, whereas the Japanese ones are.
Type 99 magnetic mine
It can be quite difficult to determine the origin of a Type 99 magnetic mine from a distance, and one really should be able to see one up close before paying for one, unless it’s coming from a reputable dealer. The main things to look for are magnets and fuzes. US made Type 99’s only have metal blocks representing the magnets on the real Japanese mines and are not actually magnetic. The fuzes will also lack any date or manufacturer markings.
Yardstick mine
Probably the most difficult mine in the entire training kit to discern from its real Japanese counterpart is the yardstick mine. Authentic examples of the yardstick mine are incredibly rare and any examples seen should be viewed through a lens of suspicion. Yardstick mines in good condition are most likely US training aids. If it’s complete with its plaster of Paris blocks, or any of the solid metal fuzes, then it is obviously a US made piece. I would suspect that any authentic Japanese yardstick mines would probably be closer to relic condition.
Final Thoughts
The US made Mine, Training Aid Set No.2, Japanese is a wonderful piece to add to any collection. The pieces included in the kit are incredibly well-made copies of the Japanese originals and offer a great opportunity to handle and study pieces of Japanese ordnance that would otherwise be almost unobtainable. These kits can be found in varying condition and in completeness. Finding a kit that is 100% complete, and in good condition can be quite challenging, the prices are always rising.
Mine training kits that are partially complete, or their individual components pop every so often on the web. These pieces are still great additions to any collection. Seeing as these pieces are becoming harder and harder to find, I would not hesitate to pick up individual pieces or a partially complete kit with its storage crate so long as the price was right. I am incredibly fortunate to be able to add this complete mine training set to my collection, and I am really looking forward to focusing on the individual pieces in later articles, so stay tuned!
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