Aside from incendiary bombs, the Japanese are reported to have at least two types of
incendiary grenades and at least one type of incendiary mortar shell. For general
information on Axis incendiary
munitions, see Tactical and Technical Trends, No. 14, p. 12.
a. Half-kilogram Incendiary Grenade
This grenade, 50-mm in diameter, approximately 5.3 inches in length, and weighing 1.1 pounds, may
be thrown by hand or projected with a heavy grenade discharger, sometimes mistakenly
called a "knee mortar," The incendiary filling (white phosphorus) is contained in a brass
body. An attachment consisting of a propellant and a percussion cap is screwed into the
base of the grenade for projection with the grenade discharger. When thrown by hand, this
attachment is removed. Before use, the safety pin is withdrawn. The safety pin serves the
double purpose of holding a light brass cover in place and of preventing downward movement
of the firing pin onto the percussion cap. The firing pin is then held off the percussion
cap by a creep spring, upward movement being prevented by the light brass cover which is
crimped in the middle and engages in a "V" groove cut around the ignition tube.
When used by hand, the head of the ignition tube is given a sharp tap to drive the
firing pin onto the percussion cap. After a delay of 4 to 5 seconds, a fuse detonates
the burster, scattering the phosphorus. When used with the grenade discharger, the
shock of discharge has the same effect as tapping the grenade when thrown by hand.
b. Incendiary Hand Grenade
This weapon has a diameter of 2.2 inches and an over-all length of 13.5 inches, including
the wooden handle 5.3 inches in length.
The incendiary filling of the grenade is composed of white phosphorus and carbon
disulfide with 41 cylindrical rubber pellets. Upon explosion, these pellets are
scattered and bounce about, igniting any inflammable matter with which they may
come in contact.
The detonating apparatus for this grenade is similar to that of the 1/2-kilogram
incendiary grenade previously described, except that the fuse gives a delay of 6 seconds.
c. 90-mm Incendiary Mortar Shell, Type '94'
The incendiary filling in this bomb is similar to the hand grenade described
in paragraph b above, being composed of white phosphorus and carbon disulfide
with 40 cylindrical rubber pellets.
The tail arrangement is designed for one primary and six secondary charges.
The total weight of the bomb is given as 11.6 pounds, the incendiary filling as 2.2 pounds, and
the burster charge as 2.8 ounces, while the over-all length is 16 inches. Its maximum
range is reported to be about 4,000 yards.
* Based on a Chemical Warfare Intelligence Bulletin, Office of the Chief, Chemical Warfare Service.