Type 97.

This is coolbert:

Those that have seen both of the Clint Eastwood Iwo Jima movie, "Flags of Our Fathers" and "Letters from Iwo Jima", will recall those specific scenes when the Japanese soldiers en masse' commit suicide, using hand grenades to do so. A live grenade held against the belly, detonation causing more or less instantaneous death.

Japanese hand grenades fuzed and primed in a particular manner [hitting against a hard object, the helmet for instance]!

Myself included, I guess a whole bunch of folks must have wondered what that was all about! Smack the grenade on the helmet prior to detonation. Just pulling the pin on the grenade was not good enough?

From a military forum on the web, thanks to Kurt L.:

"I recently watched 'Letters from Iwo Jima.' I liked the movie, bye the way. When the Japanese soldiers were committing suicide in the caves, they smacked the hand grenades on their helmet to set them off. Did they have some sort of contact fuse or was this some kind of artistic license? That seems an unusual for a hand grenade to function."

And INDEED - - Kurt L. has his question, and mine too answered, thanks to the Internet, in the proverbial heartbeat!

"Japanese WWII grenade fuses were percussion-initiated. You pull the pin, and smack the fuse on a hard surface, then the percussion cap would start burning the time fuse."

"Wasn't so strange in early 20th century - method is very simple and easy to manufacture."

"Other grenades that used same method of operation":

* "German ww1 - Eierhandgranate 1916"
* "British No.34"
* "Yugo M.17, M.35, M.38, M50R, M52R, M93, RB-100"

These were Japanese Type 97 hand grenades.

The Type 97 Hand Grenade was the standard fragmentation hand grenade of the Imperial Japanese Army and Imperial Japanese Navy SNLF [Special Naval Landing Forces] during the Second Sino-Japanese War and World War II.

"A sharp blow against a hard surface, such as a rock or combat helmet would overcome a creep spring and crush a thin brass cap, allowing the pin to hit the primer and initiate the delay sequence before throwing at the target."

Holding a live grenade against the belly, the explosion causing mortal damage to the system, shock and sudden death of an instantaneous nature, was a common way for the Japanese soldier to commit suicide during World War Two [WW2]. It was notice too that in the aftermath of the Battle of Saipan, Japanese civilians had used grenades to kill themselves, the bodies being found headless! Civilians blowing themselves apart, grenade to head, detonation resulting in climactic aftermath!!

coolbert.