In previous issues of Tactical and Technical Trends, references have been
made to some defensive tactics used by the Japanese. The following notes from
British sources give added emphasis to this subject and are reported here in order
to facilitate recognition of these tactics.
Japanese tactical methods in the defense conform basically to normal
practice, but they are characterized by a very high standard of camouflage. Except
in marshy country, where the Japanese build up to as much as 8 feet above
ground level, it is difficult to spot their positions, which are skillfully hidden under
bushes, hedges, and buildings and even under the roots of big trees. Whether
in jungle or other country, the principle of all-around defense is strictly
applied, and positions have so far presented no weak spots. Defended
areas, however small, are self-contained with regard to ammunition and food, and
they are stubbornly defended--literally to the last man. Japanese seriously
wounded have been found still grasping hand grenades which they have been too
weak to throw, and on other occasions repeated offers of quarter in a hopeless
situation have been refused.
The information given below is based on experiences in New Guinea and
the Solomons, and while principles--such as depth in the defense, all-around
defense, and the application of camouflage--do not alter, details such as the
employment of supporting weapons and the construction of defenses, will vary
considerably according to the nature of the country. This point should be remembered
when studying what the Japanese have done in the dense jungle of New Guinea, so
as to be prepared for something different in the more open spaces
of, say, Central Burma and China.
b. Organization of Defensive Position
The Japanese choose positions on commanding ground and site their
defended areas in great depth along the line of communication.
Weapons are sited to cover all approaches and are protected by booby
traps. Weapon pits are small and cleverly concealed. They normally contain
one or two men and are often linked by tunnels. Whether in swampy or dry
ground, overhead cover is often constructed.
Automatic weapons are sited to fire along prepared lines which intersect. These
lines are cut in the jungle to a height of about 2 feet, presenting a tunnel
effect. 30-caliber heavy MGs are likely to be sited well forward and sub-allotted
to platoon localities. Positions containing automatic weapons are frequently
protected by snipers in trees near the position. Men in trees have also been reported
on the flanks of positions.
In swampy areas, two types of earthworks are constructed. The first, called in the
Southwest Pacific the "bunker" type, consists of a trench with closely
timbered sides and top. The trench is covered by a mound which is built up with
coconut-log piles laid lengthwise and packed with earth. The height of the mound
and the depth of the trench vary according to the level of the swamp water. Some
mounds rise to about 8 feet above ground level. These mounds have slits at ground
level for automatic weapons, and the positions are connected by crawl trenches. The
mounds give protection to the defenders against mortar and antipersonnel
bombs and limit the effect of 25-pounder (88-mm) shells. Positions are
camouflaged with local natural materials.
The second type of earthwork is similar in appearance to the first, but it is
constructed without loopholes and used for concealment and protection from
artillery and mortar fire. Attacking troops, attracted by these raised
earthworks, tend to make them their objectives and are then caught in the
fire from posts constructed at ground level on the flanks and in rear of
In addition to the construction of these earthworks, the Japanese pay
particular attention to the careful digging of dugouts. In the Solomon Islands, for
instance, it was found that hand grenades could be thrown into Japanese dugouts
but, owing to the special construction of the entrance, they exploded harmlessly
inside without killing the occupants, who were subsequently able to emerge and
fire into the rear of our troops. In this area the dugouts were cut back into a
hillside and were sited so as to be mutually supporting. They were constructed
to hold about eight men each and were faced on the front and flanks with sand bags
and steel plates. Their layout was as shown in the
diagram (see Tactical and
Technical Trends, No. 10, p. 13).
Telephone cables are laid between defended localities, but according to
information received so far, visual methods of intercommunication, such as flag
or shutter, have not been employed.
c. Conduct of Defense
In jungle country the fire fight takes place at ranges of between 50 and 100 yards. It
has been found especially necessary to make a short pause between
igniting the fuze of a grenade and throwing it, as otherwise the Japanese are adept
at throwing them back.
The Japanese make frequent use of small local counterattacks conducted
by 8 or 10 men and led by an officer.
d. Deceptive Tactics; New Guinea
The following notes summarize some of the tactics used by the Japanese
in the New Guinea area. The extensive use again made of deceptive tactics should
(1) When the Japanese met the enemy line of skirmishers they fired all
their machine guns into the tree-tops above their opponents. As soon as
this fire was countered by Allied machine guns, the Japanese mortars
opened up on these machine-gun positions.
(2) On several occasions when the Allied line of skirmishers was met, large
numbers of Japanese ran forward and were met by a withering machine-gun
fire. They immediately turned round and fled. Allied troops with the usual cry
of "After the bastards" immediately rushed forward with fixed
bayonets. Immediately, the fleeing Japanese threw themselves on the
ground and Allied soldiers ran into machine-gun fire from the Japanese rear.
(3) In the Milne Bay area the Japanese plan was to advance and attack
during the night and then to withdraw during the daytime, leaving dozens of their
men in the tops of coconut palms, and in the jungle, with automatic weapons. As
Allied forces advanced the next day, they were harassed by these remnants. Often
the Japanese were tied in the tops of the palm trees and remained there after they
(4) There were times when it was felt that the Japanese troops might have
surrendered, but in no case did they do so. It was a question of keeping
at them until every man was killed.
(5) Counter Tactics
The plan eventually developed by Allied forces, as they advanced during
the day, was to drop a platoon or two each 4 to 5 hundred yards apart as they
advanced, and eventually they would meet the main Japanese forces. By nightfall
each of the independent posts and the main force would slash a perimeter
clearing of about 200 yards diameter around their posts, rig trip wires
at the edge, and then confidently await the Japanese night attack. This
appeared to upset the Japanese plan and proved very successful.