HAND-GRENADES AND TRENCH MORTARS
In primitive times battles were fought hand-to-hand. The first
implements of war were clubs and spears and battle-axes, all intended
for fighting at close quarters. The bow and arrow enabled men to fight
at a distance, but shields and armor were so effective a defense
that it was only by hand-to-hand fighting that a brave enemy could
be defeated. Even the invention of gunpowder did not separate the
combatants permanently, for although it was possible to hurl missiles
at a great distance, cannon were so slow in their action that the
enemy could rush them between shots. Shoulder firearms also were
comparatively slow in the early days, and liable to miss fire, and it
was not until the automatic rifle of recent years was fully developed
that soldiers learned to keep their distance.
When the great European war started, military authorities had come to
look upon war at close quarters as something relegated to bygone days.
Even the bayonet was beginning to be thought of little use. Rifles
could be charged and fired so rapidly and machine-guns could play
such a rapid tattoo of bullets, that it seemed impossible for men to
come near enough for hand-to-hand fighting, except at a fearful cost
of life. In developing the rifle, every effort was made to increase
its range so that it could be used with accuracy at a distance of a
thousand yards and more. But when the Germans, after their retreat in
the First Battle of the Marne, dug themselves in behind the Aisne, and
the French and British too found it necessary to seek shelter from
machine-gun and rifle fire by burrowing into the ground, it became
apparent that while rifles and machine-guns could drive the fighting
into the ground, they were of little value in continuing the fight
after the opposing sides had buried themselves. The trenches were
carried close to one another, in some instances being so close that the
soldiers could actually hear the conversation of their opponents across
the intervening gap. Under such conditions long-distance firearms were
of very little practical value. What was needed was a short-distance
gun which would get down into the enemy trenches. To be sure, the
trenches could be shelled, but the shelling had to be conducted from a
considerable distance, where the artillery would be immune to attack,
and it was impossible to give a trench the particular and individual
attention which it would receive at the hands of men attacking it at
close quarters.
Before we go any farther we must learn the meaning of the word
"trajectory." No bullet or shell travels in a straight line. As soon
as it leaves the muzzle of the gun, it begins to fall, and its course
through the air is a vertical curve that brings it eventually down to
the ground. This curve is called the "trajectory." No gun is pointed
directly at a target, but above it, so as to allow for the pull of
gravity. The faster the bullet travels, the flatter is this curve or
trajectory, because there is less time for it to fall before it reaches
its target. Modern rifles fire their missiles at so high a speed that
the bullets have a very flat trajectory. But in trench warfare a flat
trajectory was not desired. What was the use of a missile that traveled
in a nearly straight line, when the object to be hit was hiding in
the ground? Trench fighting called for a missile that had a very high
trajectory, so that it would drop right into the enemy trench.
HAND-ARTILLERY
Trench warfare is really a close-quarters fight of fort against fort,
and the soldiers who manned the forts had to revert to the ancient
methods of fighting an enemy intrenched behind fortifications.
Centuries ago, not long after the first use of gunpowder in war, small
explosive missiles were invented which could be thrown by hand. These
were originally known as "flying mortars." The missile was about the
size of an orange or a pomegranate, and it was filled with powder and
slugs. A small fuse, which was ignited just before the device was
thrown, was timed to explode the missile when it reached the enemy.
Because of its size and shape, and because the slugs it contained
corresponded, in a manner, to the pulp-covered seeds with which a
pomegranate is filled, the missile was called a "grenade."
Grenades had fallen out of use in modern warfare, although they had
been revived to a small extent in the Russo-Japanese war, and had
been used with some success by the Bulgarians and the Turks in the
Balkan wars. And yet they had not been taken very seriously by the
military powers of Europe, except Germany. Germany was always on the
lookout for any device that might prove useful in war, and when the
Germans dug themselves in after the First Battle of the Marne, they had
large quantities of hand-grenades for their men to toss over into the
trenches of the Allies. These missiles proved very destructive indeed.
They took the place of artillery, and were virtually hand-thrown
shrapnel.
The French and British were entirely unprepared for this kind of
fighting, and they had hastily to improvise offensive and defensive
weapons for trench warfare. Their hand-grenades were at first merely
tin cans filled with bits of iron and a high explosive in which a
fuse-cord was inserted. The cord was lighted by means of a cigarette
and then the can with its spluttering fuse was thrown into the enemy
lines. As time went on and the art of grenade fighting was learned, the
first crude missiles were greatly improved upon and grenades were made
in many forms for special service.
There was a difference between grenades hurled from sheltered positions
and those used in open fighting. When the throwers were sheltered
behind their own breastworks, it mattered not how powerful was the
explosion of the grenade. We must remember that in "hand-artillery" the
shell is far more powerful in proportion to the distance it is thrown
than the shell fired from a gun, and many grenades were so heavily
charged with explosives that they would scatter death and destruction
farther than they could be thrown by hand. The grenadier who cast one
of these grenades had to duck under cover or hide under the walls of
his trench, else the fragments scattered by the exploding missile might
fly back and injure him. Some grenades would spread destruction to a
distance of over three hundred feet from the point of explosion. For
close work, grenades of smaller radius were used. These were employed
to fight off a raiding-party after it had invaded a trench, and the
destructive range of these grenades was usually about twenty-five feet.
Hand-grenades came to be used in all the different ways that artillery
was used. There were grenades which were filled with gas, not only
of the suffocating and tear-producing types, but also of the deadly
poisonous variety. There were incendiary grenades which would set fire
to enemy stores, and smoke grenades which would produce a dense black
screen behind which operations could be concealed from the enemy.
Grenades were used in the same way that shrapnel was used to produce
a barrage or curtain of fire, through which the enemy could not pass
without facing almost certain death. Curtains of fire were used not
only for defensive purposes when the enemy was attacking, but also to
cut off a part of the enemy so that it could not receive assistance
and would be obliged to surrender. In attacks upon the enemy lines,
grenades were used to throw a barrage in advance of the attacking
soldiers so as to sweep the ground ahead clear of the enemy.
The French paid particular attention to the training of grenadiers. A
man had to be a good, cool-headed pitcher before he could be classed as
a grenadier. He must be able to throw his grenade with perfect accuracy
up to a distance of seventy yards, and to maintain an effective
barrage. The grenadier carried his grenades in large pockets attached
to his belt, and he was attended by a carrier who brought up grenades
to him in baskets, so that he was served with a continuous supply.
LONG-DISTANCE GRENADE-THROWING
All this relates to short-distance fighting, but grenades were also
used for ranges beyond the reach of the pitcher's arm. Even back in
the sixteenth century, the range of the human arm was not great enough
to satisfy the combatants and grenadiers used a throwing-implement,
something like a shovel, with which the grenade was slung to a greater
distance, in much the same way as a lacrosse ball is thrown. Later,
grenades were fitted with light, flexible wooden handles and were
thrown, handle and all, at the enemy. By this means they could be slung
to a considerable distance. Such grenades were used in the recent war,
particularly by the Germans. The handle was provided with streamers
so as to keep the grenade head-on to the enemy, and it was usually
exploded by percussion on striking its target. These long-handled
grenades, however, were clumsy and bulky, and the grenadier required a
good deal of elbow-room when throwing them.
[Illustration: FIG. 3. A rifle grenade fitted to the muzzle of a rifle]
A much better plan was to hurl them with the aid of a gun. A rifle made
an excellent short-distance mortar. With it grenades could be thrown
from three to four hundred yards. The grenade was fastened on a rod
which was inserted in the barrel of the rifle and then it was fired out
of the gun by the explosion of a blank cartridge. The butt of the rifle
was rested on the ground and the rifle was tilted so as to throw the
grenade up into the air in the way that a mortar projects its shell.
STRIKING A LIGHT
The lighting of the grenade fuses with a cigarette did very well
for the early tin-can grenades, but the cigarettes were not always
handy, particularly in the heat of battle, and something better had
to be devised. One scheme was to use a safety-match composition on
the end of a fuse. This was covered with waxed paper to protect it
from the weather. The grenadier wore an armlet covered with a friction
composition such as is used on a safety-match box. Before the grenade
was thrown, the waxed paper was stripped off and the fuse was lighted
by being scratched on the armlet. In another type the fuse was lighted
by the twisting of a cap which scratched a match composition on a
friction surface. A safety-pin kept the cap from turning until the
grenadier was ready to throw the grenade.
The Mills hand-grenade, which proved to be the most popular type used
by the British Army, was provided with a lever which was normally
strapped down and held by means of a safety-pin. Fig. 4 shows a
sectional view of this grenade. Just before the missile was thrown,
it was seized in the hand so that the lever was held down. Then the
safety-pin was removed and when the grenade was thrown, the lever would
spring up under pull of the spring _A_. This would cause the pin _B_
to strike the percussion cap _C_, which would light the fuse _D_. The
burning fuse would eventually carry the fire to the detonator _E_,
which would touch off the main explosive, shattering the shell of the
grenade and scattering its fragments in all directions. The shell of
the grenade was indented so that it would break easily into a great
many small pieces.
[Illustration: FIG. 4. Details of the Mills hand grenade]
There were some advantages in using grenades lighted by fuse instead
of percussion, and also there were many disadvantages. If too long a
time-fuse were used, the enemy might catch the grenade, as you would
a baseball and hurl it back before it exploded. This was a hazardous
game, but it was often done.
[Illustration: FIG. 5. A German parachute grenade]
Among the different types of grenades which the Germans used was
one provided with a parachute as shown in Fig. 5. The object of the
parachute was to keep the head of the grenade toward the enemy, so that
when it exploded it would expend its energies forward and would not
cast fragments back toward the man who had thrown it. This was a very
sensitive grenade, arranged to be fired by percussion, but it was so
easily exploded that the firing-mechanism was not released until after
the grenade had been thrown. In the handle of this grenade there was
a bit of cord about twenty feet long. One end of this was attached to
a safety-needle, _A_, while the other end, formed into a loop, was
held by the grenadier when he threw the grenade. Not until the missile
had reached a height of twelve or thirteen feet would the pull of the
string withdraw the needle _A_. This would permit a safety-hook, _B_,
to drop out of a ring, _C_, on the end of a striker pellet, _D_. When
the grenade struck, the pellet _D_ would move forward and a pin, _E_,
would strike a cap on the detonator _F_, exploding the missile. This
form of safety-device was used on a number of German grenades.
[Illustration: FIG. 6. British rifle grenade with a safety-device which
is unlocked by the rush of air against a set of inclined vanes, _D_,
when the missile is in flight]
The British had another scheme for locking the mechanism until after
the grenade had traveled some distance through the air. Details of this
grenade, which was of the type adopted to be fired from a rifle, are
shown in Fig. 6. The striker _A_ is retained by a couple of bolts, _B_,
which in turn are held in place by a sleeve, _C_. On the sleeve is a
set of wind-vanes, _D_. As the grenade travels through the air, the
wind-vanes cause the sleeve _C_ to revolve, screwing it down clear of
the bolts _B_, which then drop out, permitting the pin _A_ to strike
the detonator _E_ upon impact of the grenade with its target.
[Illustration: FIG. 7. Front, side, and sectional views of a
disk-shaped German grenade]
[Illustration: FIG. 8. A curious German hand grenade shaped like a hair
brush]
The Germans had one peculiar type which was in the shape of a disk. In
the disk were six tubes, four of which carried percussion caps so that
the grenade was sure to explode no matter on which tube it fell. The
disk was thrown with the edge up, and it would roll through the air.
Another type of grenade was known as the hair-brush grenade because it
had a rectangular body of tin about six inches long and two and three
quarter inches wide and deep, which was nailed to a wooden handle.
MINIATURE ARTILLERY
Hand-artillery was very effective as far as it went, but it had its
limitations. Grenades could not be made heavier than two pounds in
weight if they were to be thrown by hand; in fact, most of them were
much lighter than that. If they were fired from a rifle, the range was
increased but the missile could not be made very much heavier. TNT is
a very powerful explosive, but there is not room for much of it in a
grenade the size of a large lemon. Trench fighting was a duel between
forts, and while the hand-artillery provided a means of attacking the
defenders of a fort, it made no impression on the walls of the fort.
It corresponded to shrapnel fire on a miniature scale, and something
corresponding to high-explosive fire on a small scale was necessary
if the opposing fortifications were to be destroyed. To meet this
problem, men cast their thoughts back to the primitive artillery of
the Romans, who used to hurl great rocks at the enemy with catapults.
And the trench fighters actually rigged up catapults with which
they hurled heavy bombs at the enemy lines. All sorts of ingenious
catapults were built, some modeled after the old Roman machines. In
some of these stout timbers were used as springs, in others there were
powerful coil springs. It was not necessary to cast the bombs far. For
distant work the regular artillery could be used. What was needed was a
short-distance gun for heavy missiles and that is what the catapult was.
[Illustration: Press Illustrating Service
A 3-inch Stokes mortar and two of its shells]
[Illustration: Press Illustrating Service
Dropping a shell into a 6-inch trench mortar]
But the work of the catapult was not really satisfactory. The machine
was clumsy; it occupied too much space, and it could not be aimed very
accurately. It soon gave way to a more modern apparatus, fashioned
after the old smooth-bore mortars. This was a miniature mortar, short
and wide-mouthed. A rifled barrel was not required, because, since
the missile was not to be hurled far, it was not necessary to set it
spinning by means of rifling so as to hold it head-on to the wind.
GIANT PEA-SHOOTERS
Better aim was secured when a longer-barreled trench mortar came to
be used. In the trench, weight was an important item. There was no
room in which to handle heavy guns, and the mortar had to be portable
so that it could be carried forward by the infantry in a charge. As
the walls of a light barrel might be burst by the shock of exploding
powder, compressed air was used instead. The shell was virtually blown
out of the gun in the same way that a boy blows missiles out of a
pea-shooter. That the shell might be kept from tumbling, it was fitted
with vanes at the rear. These acted like the feathers of an arrow to
hold the missile head-on to its course.
[Illustration: Courtesy of "Scientific American"
The Maxim Machine-gun Operated by the Energy of the Recoil]
[Illustration: Courtesy of "Scientific American"
Colt Machine-gun partly broken away to show the Operating Mechanism
Gas from port _A_ pushes down piston _B_, rocking lever _C_, which
compresses coil-spring _D_. The cartridge fed into the gun by wheel
_E_, is extracted by _F_, raised by _G_ to breech _H_, and rammed in by
bolt _I_. _J_, piston firing-hammer.]
The French in particular used this type of mortar and the air-pump was
used to compress the air that propelled the shell or aërial torpedo,
or else the propelling charge was taken from a compressed-air tank.
Carbon-dioxide, the gas used in soda-water, is commonly stored in
tanks under high pressure and this gas was sometimes used in place
of compressed air. When the gas in the tank was exhausted the latter
could be recharged with air by using a hand-pump. Two or three hundred
strokes of the pump would give a pressure of one hundred and twenty to
one hundred and fifty pounds per inch, and would supply enough air to
discharge a number of shell. The air was let into the barrel of the
mortar in a single puff sufficient to launch the shell; then the tank
was cut off at once, so that the air it contained would not escape and
go to waste.
THE STOKES MORTAR
However, the most useful trench mortar developed during the war was
invented by Wilfred Stokes, a British inventor. In this a comparatively
slow-acting powder was used to propel the missile, and so a thin-walled
barrel could be used. The light Stokes mortar can easily be carried
over the shoulder by one man. It has two legs and the barrel itself
serves as a third leg, and the mortar stands like a tripod. The two
legs are adjustable, so that the barrel can be inclined to any desired
angle. It took but a moment to set up the mortar for action in a trench
or shell-hole.
[Illustration: FIG. 9. Sectional view of a 3-inch Stokes mortar showing
a shell at the instant of striking the anvil]
[Illustration: FIG. 10. A 6-inch trench mortar shell fitted with
tail-vanes]
Curiously enough, there is no breech-block, trigger or fire-hole in
this mortar. It is fired merely by the dropping of the missile into the
mouth of the barrel. The shell carries its own propelling charge, as
shown in Fig. 9. This is in the form of rings, _A_, which are fitted
on a stem, _B_. At the end of the stem are a detonating cap and a
cartridge, to ignite the propellant, _A_. At the bottom of the mortar
barrel, there is a steel point, _E_, known as the "anvil." When the
shell is dropped into the mortar, the cap strikes the anvil, exploding
the cartridge and touching off the propelling charge, _A_. The gases
formed by the burning charge hurl the shell out of the barrel to a
distance of several hundred yards.
The first Stokes mortar was made to fire a 3-inch shell, but the mortar
grew in size until it could hurl shell of 6-inch and even 8-1/2-inch
size. Of course, the larger mortars had to have a very substantial
base. They were not so readily portable as the smaller ones and they
could not be carried by one man; but compared with ordinary artillery
of the same bore they were immeasurably lighter and could be brought to
advanced positions and set up in a very short time. The larger shell
have tail-vanes, as shown in Fig. 10, to keep them from tumbling when
in flight.