Type 4 Japanese ceramic grenades 

During 1944 and 45 the Empire of Japan was experiencing repeated military defeats and the war efforts in Japan were reaching a serious crisis of manufacturing material and capacity. It was during this desperate time period that the Type 4 ceramic grenade was introduced. It was designed to be used by both the Imperial Japanese military as well as civilians on the home islands. Technically, every single Japanese subject was mobilized under the general mobilization orders of the emperor. Every civilian was considered a member of the Imperial Japanese military and expected to fight to the death to defend Japan. The type 4 was probably 1^st encountered by US troops during the invasion of Iwo Jima in February of 1945. It was later encountered in larger numbers during the invasion of Okinawa. 

During the WW2 era, Japanese grenades of most varieties were known for their frequent failure to detonate due to poor manufacturing processes, low quality explosive components and poor storage and handling by Japanese troops. In one instance I read, an Imperial Japanese Army soldier was wounded and about to be captured, so he decided to kill himself with his Type 97 fragmentation grenade, which was a common practice. Under the rules of the Japanese code of honor, bushido, being captured alive brought dishonor upon yourself and your family, which carried tangible negative impacts for all. However, the soldier’s grenade failed to detonate, and he was captured alive by British soldiers, nursed back to health by his captors and went on to write his memoirs as an old man, to his disappointment.  

The Type 4 grenade was absolutely notorious for failing and that may be the reason so many are available to collectors today. The ceramic bodies of the grenades were manufactured in traditional Japanese ceramic manufacturing kilns that had been conscripted for the purpose. Some examples in existence today bear kiln numbers identifying the manufacturers, but most that I have encountered do not.

                      

Kiln markings on Type 4 grenade bodies. 

Type 4 grenade bodies were normally glazed and fired, the colors ranging from stark white, to brown to black, some having flat bottoms but most having rounded bottoms, and the quality of the finish varying from amazingly beautiful to horrid. I have seen a Type 4 in pink and one in yellow, but the vast majority range from white to brown.

        

 A round-bottom type 4 grenade body (left) and a flat-bottom version (right)

 

The ceramic body was filled with an explosive charge and a cheap fuse made of wood and rubber casing with an unreliable time delay was inserted into the neck of the grenade body. The fuse was ignited by means of a match type composition which was struck upon a small friction block included with the grenade. The fuse and block were covered with a flexible rubber cover which was further secured with a flat piece of cotton strapping. Any moisture that contacted the match compound of the fuse would cause it to crumble and not ignite. If the user successfully ignited the grenade and threw it towards their target, they had to pray that the ceramic body did not break upon impact because a broken grenade body would allow the explosive charge to fall out and the grenade would not be effective. If all went according to plan and the grenade fuse lit properly and the charge detonated, the ceramic bodies often split apart into large segments, reducing the effectiveness of the fragmentation effect desired.

Later ceramic grenade bodies had segmentation lines in them to hopefully increase the effectiveness of the grenade.  

 

Ceramic type 4 with segmentation cast into the body. 

It is probable that ceramic grenade bodies were manufactured into the millions. Their availability up until recent years has made them cheap and plentiful. Well into the 1980s it was common to find them for sale with hand painted decorations and for sale in exchanges and shops catering to US GIs across Japan. 

 

Painted Type 4 grenade bodies sold as souvenirs in US military exchanges and presented as mementos of service in Japan.

At one point in the 1960s, according to a neighbor and retired US Navy Master Chief Petty Officer, these grenades were used by the US Navy to test underwater welds on US Navy ships. The Navy replaced the Japanese fuses and explosives with US fuses and explosives and dropped them into the water next to US ships to test weld and hull integrity with no risk of damage to the steel hulls. 

 

Not long after the war the grenade bodies were destroyed in large numbers as well and unceremoniously dumped, as seen here.

 

 

The broken remnants of Japanese ceramic grenades dumped in the countryside.

None the less, Type 4 grenades are still encountered, complete with fuses and explosives. As recently as September 2022, one was found by a US service member snorkeling off the coast Japan near Misawa Air Base. The US Airman brought it into his home and only realized what it was when he was researching the item. He removed the grenade from his home and called US Air Force EOD to come deal with it. Not surprisingly, it was deemed non-threatening after having soaked in the salt water since 1945. The chance that you may encounter a live grenade in Japan or the Pacific Theater of the war are still high enough that it is recommended that you not take them home but call authorities instead.

  

 Type 4 grenade found off the coast of Japan in September 2022, with fuse still in the body. Stars and Stripes photos.

 

Today, the Type 4 grenade has its place in any collection of WW2 Japanese weapons and militaria, inert ordnance or curiosities. As a young collector I knew what these grenade bodies were and their abundance combined with their low price kept me from being very interested in them. Now, in early 2023, a single Type 4 grenade body can sell for hundreds of dollars depending on its different features. A finely glazed and beautiful piece may sell for upwards of $300 in the US. Shocking, considering that similarly finished Japanese ceramics that have a real function in today’s world, such as Sake bottles and fine artworks, can sell for far less. I believe the Type 4 grenade bodies are a bellwether for the prices of Japanese WW2 memorabilia in general. For some time, Japanese WW2 items were always considered to be of less value than comparative items from WW2 Germany. This is changing. I believe that Japanese items are catching up to German items in price due to demand, at least in the US. In the meantime, Type 4 grenades can still be found for reasonable prices if you know what you are looking for.