Direction for firing in field and mountain artillery

The replacement of the first Bulgarian firing rules, the “Red booklet”, was a long and complex matter. A preliminary text was published in 1897. Some little imperfections and inaccuracies were emended two years later, when a new improved version was issued. It constituted a remarkable improvement on firing discipline, giving also a detailed account of the main novelties introduced by the foreign armies, especially in the fire regulations published in Russia in 1892, in Germany in 1893, and in Italy in 1894. The provisional text was intensively tested for five years, and the Наставление за стрелбата въ полската и планинската артилерия (Direction for firing in field and mountain artillery) was finally published in 1902, remaining effective till 1905, when quick-firing guns were introduced.

The direction included five sections :

I. Ballistic data on guns and projectiles.

II. Preparation of fire.

III. Measuring and determination of the range.

IV. Firing rules.

V. Firing practice and its accountancy.

Guns and projectiles. At the end of 19^th Century the Bulgarian artillery was equipped with Krupp guns, having all the same system, cylindro-pneumatic wedge breech mechanism, and uniform calibre, 87mm for field and 75mm for mountain artillery. Old 75mm field guns, regarded as too light and not powerful enough, had been assigned to the reserve. The only exception was a little number of 75mm Schneider-Canet mountain guns with swinging block breech mechanism purchased in 1897. All these guns used three kinds of projectiles: common shells against animate and inanimate targets, shrapnel against animate targets and case shots against close attacks at a range of 400 m at most. The shrapnel was provided with double – time and percussion – fuze, and could burst both into the air and at the impact on the ground. The common shell was equipped only with percussion fuze that worked on impact.

Conduct of fire. The adjustment was based on the calculus of the probabilities, while numerical quantities and measuring depended on the extent of the dispersion and the law of probability. The first condition to adjust guns quickly was an accurate determination of the distance of the target. As a rule the distance was estimated by eye, but it could be also measured on a map, obtained by means of a rangefinder, or calculated by the sound. The determination of the distance was obtained by the different effect that well-known objects (men, horses, carts, and so on) put at various distances had on the eyes, or by halving a given distance to reduce it to a distance that anybody was accustomed to estimate accurately (usually 300-500 m). The firer should gain the ability to estimate distances very closely by eye by means of constant practice, in different atmospheric conditions and in various places. In action nevertheless the distances were often underestimated.

Fire for adjustment (пристрелка). It was usually carried out with percussion shells, since the dense smoke produced by their burst was more easily observed than the smaller and more quickly dissipated smoke of the shrapnel. If there were not data about the range and the deviation of the shots with respect to the target could not be determined, the corrections should not be lower than 200 m. The bracket could be narrowed down only if the range had been carefully predetermined. If the first shot was short, the range was increased; if over, it was decreased; and shots were fired successively increased or decreased in range until the high bracket was obtained. Then the bracket was successively reduced by halving the last bracket obtained as far as the 100 m bracket was obtained. When the deviation of the shots could be determined, halving was abandoned and the bracket was adjusted using the deviation observed. As soon as the 100 m bracket was obtained, the final limit was repeated with another shot and if the straddle was obtained, the fire continued without changing the sight; otherwise the fire was directed at the middle of the low bracket and the limits of the 100 m bracket were repeated. The most likely height of the sight should be verified firing a group of six shots. If 2 – 4 shots were short the adjustment was regarded as concluded and the guns shifted to fire for effect. With percussion fire the bracket was narrowed down up to 50 m. With time fire the height of burst was adjusted setting the fuze of the shrapnel by hands, only after the verifying group.

Shrapnel fire. Shrapnel time fire as a rule was employed for the attack of animate objects, such as troops moving or staying in position. It did not require a full adjustment, but only to correct the distance in order to overspread the area of the target with the shrapnel bullets. In order to shorten the time for adjustment, as son as the 100 m bracket had been obtained, the whole battery started firing with the time fuze set behind the final limit. When there was a difference between the setting of the fuze and the elevation, the first two shots were fired to set the fuze in order to give a burst above the horizon. An accurate adjustment of the height and the interval of burst occurred only after the first series of six shots. Time fire was considered good, when, out of six shots, only one burst behind the target and the normal interval of burst was not greater than 100 m, or only one burst was low or on graze. When there was some doubt about the range, 2 – 6 verifying shots were fired, changing the fuze alone or either the fuze and the elevation.

Common shell fire. Percussion fire was principally employed for the destruction of material objects, such as walls, buildings, obstacles, artillery materiel, etc. (стрелба за разрушение, fire for demolition). At mid ranges it could pierce an earthwork 2 m thick, a brickwork 0.75 m thick, and a wooden palisade 0.35 m thick. To obtain effect upon such targets, the shell should hit them directly, requiring a more accurate adjustment. Therefore the bracket should be narrowed down up to 50 m. To open a breach 20 m long in a wall 2000 m long and 2 m large an 87mm battery needed about 120 common shells, while to destroy a four gun battery under covered 24-30 common shells. Thin walls (up to 30 cm) were demolished with shrapnel fire.

It was employed also against animate objects, where it worked by means of the splinters of the explosion. The 87mm common shell scattered around 120 splinters in a cone-shaped crater, with an angle of dispersion of 50°-60°, 1½ – 2 greater than the angle of descent. They were lethal up to 80 m in front and 50 m sideways. The effect of the common shell depended upon the character of the ground and the distance from the target. With animate targets high up to 1.70 m, the greatest effect was obtained when it fell in front of the target : up to 20 m at close range, 10 m at medium range, and on the target itself at great range. But if it fell at more than 40 m, 20 m and 5 m respectively, it was ineffective. Except at close range, against animated targets its effect was weak, and at every range it could be replaced by shrapnel with time and percussion fuze.

Case shot fire. It was employed only against standing targets at close ranges. The case shot was a cylindrical zinc case filled with round balls. When fired, the case disintegrated already in the barrel and its splinters and the balls spread out in a conical form, causing a wide swath of destruction. 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 – 500 m.

Fire for effect (стрелба на поражение). It comprised three different methods of fire :

– fire by gun (огън по оръдейно) : at an order of the battery commander each gun fired independently after loading and being laid. It was employed as a rule with case shot, at close range (less than 1500 m) to increase the rapidity of fire at the utmost; with case shot it was always used, without waiting for a special order.

– fire in succession (огън по редове) : at an order of the battery commander, each gun of the battery, beginning from leeward, fired a single discharge in regular order from one flank to the other, with a set interval; it could be ordinary (обикновен), rapid (бърз) or cursory (бегъл). The speed depended on the easiness of the observation of fire and on the fighting situations. Ordinary fire was employed when the battle dragged on, the ammunition were scarce, the observation was difficult or against a moving target, after the determination of the bracket. Cursory fire was employed for very brief period only when the battery commander could not direct fire by person and the observation was unnecessary, especially in close combat or against moving target entered into the shelled area (i.e. to repel an attack). Rapid fire was employed in the same situations, but in this case the fire was directed by the section commanders.

– fire by salvos (залпов огън) : at an order of the battery commander all the guns of the battery simultaneously fired a single discharge. It was often employed in adjustment in order to increase the smoke produced by the explosion of the shells and facilitate the observation when the smoke ball of a single shell could not be seen with sufficient clearness or in fire for effect to produce a great simultaneous effect on the target. It could be carried also by section, at an order of the section commander.

Firing practice. As for the instruction of the personnel, the direction considered the demonstrative, training, fighting (by battery, artillery division or artillery mass) and inspection fire.

Preliminary or demonstrative fire (подготвителна or показна стрелба) took place at the beginning of the school year to show to the recruits the different artillery shots and their effects. It was employed a gun of every artillery division. Every gun shot 11 rounds, and changing in sequence projectile, sight, deflection, elevation, fuze and so on, the recruits could see how the shot change. Actually this practice was a legacy of the old rules, when the gunner should not only serve at the gun, but also have a little knowledge of the firing theory.

With training fire (учебна стрелба), officers and men were trained in firing, got accustomed to the shots, learnt how to measure angle of site and deflection, to estimate the effect of wind and so on, seeing how to apply the firing rules in the different situations. The training fire was carried out near the quarters of the regiment, to allow all the personnel to take part in it. The Artillery Inspection estimated the number of rounds required according with the number of the officers who should be trained.

Fighting fire (бойна стрелба) was executed in an unknown place in strict connection with tactical tasks. Battery fighting fire was carried out by every battery commander and senior officer. It began with the fire for adjustment and ended with one or two of salvos of fire for effect. The rule was 12-13 shells and 16-18 shrapnel. The Artillery Inspection estimated the number of rounds required according with the number of the officers who should be trained, and not with the number of the battery involved. Artillery division fighting fire was carried out every year with 80 rounds per battery in the presence of all effective officers and men. Mass artillery fighting fire had the same traits of the division fire.

Inspection fire (прегледна стрелба) was carried out at the presence of the higher ranks officers. The Direction did not manoeuvre fire with the three branches of the Army.

After every day of firing practice a report was written both by the gunners and the observing officer, along with a journal of firing and lists for processing the effects of the fire. The examination covered both the tactical action and the technical aspects (estimate of firing data, ways of sighting and firing to the target, fuze-setting, observation). The results obtained were of great use in discovering defects of materiel and bad lying. With the journals collected from the drill of the whole artillery the Artillery Inspection made a statistical analysis and made its conclusions from it. These documents were read and examined by the officers during their winter tactical lessons.