Direction for firing in field and mountain QF artillery
rearmament of the Bulgarian artillery with modern quick-firing guns, occurred
in 1904, required the introduction of new firing rules to replace those
published only two years before, in
Between 1905 and 1908 the new guns were intensively tested and finally the revised standard version of the Наставление за стрелбата въ полската и планинската скорострелна артилерия was published in 1908, followed in 1909 by a detailed exposition written by col. Kalin Naydenov (Новото наставление на стрлбата в полската и планинската артилерия на практика, Sofia 1909), that covered only the first four section of the Direction.
Basically the direction dealt with the quick-firing guns, but gave also some instructions about the employment of the old not quick-firing guns on the new conditions. It included five sections :
I. Ballistic data concerning guns and projectiles.
II. Measure of the dispersion and calculation of the corrections for shrapnel fire.
III. Preparation of fire : determination of the range, direction of fire from covered positions, measure of the angle of site, observation of the bursts.
IV. Determination of the primary data: fire for adjustment and fire for effect.
V. Kinds of fires : demonstrative, training and fighting fire. Instructions for writing firing reports.
The direction included also the firing tables of all kinds of field and mountain guns adopted by the Bulgarian artillery.
Generalities rules. The artillery took part in the combat only with its fire. Quick-firing artillery shoot to break down any resistance with a rapid and powerful fire of short duration from opportune and well chosen positions at the most important targets in a particular moment. With the enormous increase in fire effect due to the introduction of magazine rifles and quick-firing artillery, troops, and especially infantry, did not expose themselves except for a very short time to the artillery fire, utilizing to the utmost all available cover. To succeed, the fire for effect should begin as far as the objectives appeared, and consequently the process of adjustment should be shortened as much as possible. The Direction did not prescribed precise ranging against a definite target, but to cover a considerable extent with shrapnel bullets, to block every attempt to every object to move about or remain there uncovered, without being put out of action.
Projectiles. The Direction examined all kinds of projectiles employed both by quick-firing and not quick-firing guns, describing in detail their main features and their effects. It considered also the projectiles fired by 120mm not quick-firing howitzers assigned to the heavy field artillery, and by the 105mm quick-firing light field howitzer, that at that time the Bulgarian Army intended to built in France. At that time the 120mm not quick-firing howitzer was equipped only with shrapnel and common shells, but later it received also Schneider built torpedo shells.
Time shrapnel was regarded as the main projectile of field and mountain artillery against all animate targets that were not under cover. It contained about 300 lead bullets (200 for mountain guns), that, spreading out from the point of burst in the air, formed a sheaf and covered a space of considerable width and depth. Consequently shrapnel fire did not demand a complete adjustment, being sufficient to approximate to the target. In addition shrapnel contained a smoke-producing composition called colophan to make the burst more visible and facilitate the adjustment. This characteristic could be used also for tactical purposes. The rapid fire of a quick-firing battery with smoke-producing shrapnel made a dense cloud of smoke in front of the enemy line, preventing him from taking an effective aim or protecting the attacking troops. Shrapnel was equipped with a double action fuze, which permitted not only to change at will the point of burst (time fire), but also to burst on graze (percussion fire).
When the shrapnel burst, the body fell 10-
At a range of 2500 m and with an interval of burst of 50 m, the average density of hit was :
– 75mm QF and 87mm not QF field guns 1.5;
– 105mm QF field howitzer 1;
– mountain guns 0.5.
Percussion shrapnel usually burst after having hitting the ground or after having ricocheting. In this way it changed a little its direction and greatly reduced its final velocity and therefore the living force of the bullets. Against animate targets it was less effective than time shrapnel, but it could destroy small inanimate targets like bridges, thin walls, fences, light shelter. It could be used against shielded artillery, when high explosive shells were lacking.
explosive shell was used either against shielded batteries at a range of
Even at close range and with hard ground it required a very careful adjustment, since its effect was very local. It could be successfully employed to harass the occupant of the hostile trenches, waiting the moment when the troops were forced to man their parapets. Having a very sensitive fuze the H.E. shell burst as soon as hit the ground, without ricocheting, making two cones of dispersion : the lower one hit the target, while the upper one scattered upward and was almost inoffensive. The angle of the cone of dispersion was between 110°-140°. The explosion gave a very great number of splinters (even 500-700), which, reaching a very high speed (up to 600 m/s), could inflict disabling wounds, if the target was at 30-40 paces. Their action in deep, however, was small and at a distance of more than 50 paces from the bursting point they were almost useless.
Torpedo shell was the most powerful projectile of the field
artillery. It was employed by the field howitzers to destroy every kind of
inanimate targets. It was equipped with a delay-action fuze, when it should
penetrate the roof of splinters proof before exploding, but it was equipped
with a simple percussion fuze when it should explode on impact. It was able
to messed up earthworks, destroy armoured shelters and sound buildings and
sweeping away every kind of obstacle that might meet with
on the battlefield. The most powerful
effect was produced when it fell at an angle greater than 30° on a stiff
ground. In this case it made a crater
Field howitzer shrapnel had almost the same action of gun shrapnel, the main differences were :
– the interval of burst should be lower, since its trajectory was steeper;
– the density of hits was greater and the beaten area wider, since it contained more bullets;
– the power of penetration of the bullets was greater, since they were heavier.
Firing at uncovered animate targets, the howitzers employed the full charge to obtain a sloping trajectory, on the contrary, firing at troops under cover, they employed the low charge to obtain a steep trajectory.
Common shell was used only by not quick-firing guns against
animate and inanimate targets. Against shielded guns it was preferred to the
shrapnel. Against animate targets at mid range, it was effective when it
burst no more than 20 m in front of the target and no more than 3-4 m behind
it. At close range and against high targets, the extent of the area of burst
could be little greater, increasing up to 30 m. Against wide animate targets
it was employed only out of the sphere of action of the shrapnel. At
mid ranges it could pierce an earthwork
Case shot used only by not quick-firing guns to beat off close
attacks at a range of 400 m at most. The cone
of dispersion of the balls had an angle of opening of 6° with an axis of
dispersion of 1/10 of the length and a range of only 400 –
The effect of shrapnel fire was somehow affected by the range, the interval of burst, the height of burst, the size of the targets, the ground and the shelters.
Increasing the range, the shrapnel fire became less effective, since the
velocity of the bullets decreased and, with it, their striking power; the
trajectory became steeper and the bullets could not ricochet on the terrain;
the combustion of the fuze became less regular; the extent of the effective
area decreased. The greater effect was obtained up to
bursting too far in front of the target and those bursting in the air above
the target produced little of no effect. Therefore the interval of burst of the shrapnel, i.e. the horizontal distance
between the point of burst and the target, should be carefully set, since
shrapnel were really effective only if they burst close to the target : the
greater was the interval of burst, the greater was the dispersion of bullets,
the less the density, and consequently the smaller the number of hits. The
normal interval of burst was put at
height of burst, i.e. the vertical distance of the point of burst
above the horizon, should be carefully adjusted, taking into account
that the combustion of the fuze was not always uniform. A probable deviation
The effect of shrapnel fire increased with the size of the targets : the greatest was their surface, the more vulnerable they were. The density of hits required to hit a target could be easily obtained, knowing the area of surface exposed, which, according with the estimate of that time, were as follows :
horse and rider, side view –
horse and rider, front view –
skirmisher, standing –
skirmisher, kneeling –
skirmisher, lying down –
skirmisher, covered –
Since shrapnel burst in air, the effect of time fire depended less upon the character of the terrain than any other kind of projectile. Nevertheless it had some influence. Indeed, if the terrain in front of the target was level and hard, the bullets would ricochet easily and loose little of their velocity, being able to produce still effective hits. But if it was broken or soft, the majority of the bullets would imbed themselves in the ground. The same happened when the slope of ground was rising at the target. In addition the width of the cone of dispersion was greatest when the slope of the ground was equal to the angle of fall of the unexploded shrapnel. As the slope of the ground increased, the width of the zone of dispersion decreased. When the slope of the ground was greater that the angle of fall of the lowest bullet, no effect was produced at all.
Shrapnel fire was ineffective against troops under cover, i.e. located immediately
in rear of parapets or any kind of obstacle, since behind them there was a
blank space, where the bullets could not penetrate or were powerless and
ineffective. The depth of the blank space could be calculated multiplying the
height of the cover by 8, 6, 4, 3 for ranges of 1, 2, 3, 4 km respectively.
The closer the range, the most sloping the trajectory, the broadest the blank
space : with a cover
fuze correction. Shrapnel
usually employed the double-action delay fuze. With quick-firing field guns
the fuze was adjusted mechanically with a special fuze-setter,
while with not quick-firing guns it was set manually. For quick-firing field guns the fuze was calibrated with a height of
Preparation of fire. The primary firing data, that should be determined, were : 1) range, 2) deflection, 3) angle of sight – for indirect laying, 4) corrector – for time fire, 5) width, depth and kind of the target.
range to the target could be
measured on a map, or obtained by telemeter, battery telescope or field
glasses, or estimated by eye or by sound. While previously the distance was
estimated mainly by eye, this Direction
focused its attention to the use of the rangefinder. When it was published the Bulgarian Army employed
mainly the Souchier prismatic telemeter, adopted also by the Russian Army,
but the Goerz rangefinder
The range according with the effectiveness of the fire were :
– for field guns: up to 1500 m close, from 1500 m to 3500 m mid, more than 3500 m great;
– for mountain guns: up to 1500 m close, from 1500 m to 3000 m mid, more than 3000 m great.
correction in deflection was
necessary to overcome the effects of wind and drift. With moderate winds the deflection should be
changed, adding or subtracting 1 millième, depending upon the direction of
the wind, 2 millièmes with strong winds. With field guns every
When the guns were placed in masked or covered positions, before firing, the battery commander had to determine the angle of sight. It could be measured by the battery telescope, by means of the sight and quadrant, by means of the graduated ruler, calculated on the map or obtained through theoretical formulas.
The corrector was used to fix the height of burst of time-fuzed shrapnel, as shown above.
Since nearly all kinds of objects might be the target of the artillery fire – infantry, cavalry and artillery in many different formations, field fortifications, bridges, buildings, woods, balloon etc. – to be really effective the fire should be distributed and adapted to the main features of each of them.
Finally the Direction explained how to prepare perspective sketch, that could be used to :
– to easily orient the high commander, when they arrived at the position or at the observation post ;
– to direct and control the fire of an artillery division of a group of batteries, when its head was distant;
– to offer to the battery commander information about the firing data related to different points of the battlefield;
– to permit to the observers to show to the firing guns about the position of their targets.