CANNON PROJECTILES

[Dept of PMM Artists & things]

Cannon Projectiles

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There are four different types of artillery projectiles which, in one form or another, have been used since very early times:

Battering projectiles (solid shot) Exploding shells Scatter shot (case or canister, grape, shrapnel) Incendiary and chemical projectiles

At Havana, Cuba, in the early days, there was an abundance of round stones lying around, put there by Mother Nature. Artillerists at Havana never lacked projectiles. Stone balls, cheap to manufacture, relatively light and therefore well suited to the feeble construction of early ordnance, were in general use for large caliber cannon in the fourteenth century. There were experiments along other lines such as those at Tournay in the 1330's with long, pointed projectiles. Lead-coated stones were fairly popular, and solid lead balls were used in some small pieces, but the stone ball was more or less standard. Cast-iron shot had been introduced by 1400, and, with the improvement of cannon during that century, iron shot gradually replaced stone. By the end of the 1500's stone survived for use only in the pedreros, murtherers, and other relics of the earlier period. Iron shot for the smoothbore was a solid, round shot, cast in fairly accurate molds; the mold marks that invariably show on all cannonballs were of small importance, for the ball did not fit the bore tightly. After casting, shot were checked with a ring gauge (fig. 41)—a hoop through which each ball had to pass. The Spanish term for this tool is very descriptive: pasabala, "ball-passer." Shot was used mainly in the flat-trajectory cannon. The small caliber guns fired nothing but shot, for small sizes of the other type projectiles were not effective. Shot was the prescription when the situation called for "great accuracy, at very long range," and penetration. Fired at ships, a shot was capable of breaching the planks (at 100-yard range a 24-pounder shot would penetrate 4-1/2 feet of "sound and hard" oak). With a fair aim at the waterline, a gunner could sink or seriously damage a vessel with a few rounds. On ironclad targets like the Monitor and Virginia (Merrimack), however, round shot did little more than bounce; it took the long, armor-piercing rifle projectile to force the development of the tremendously thick plate of modern times. Round shot Canister shot (or case shot) Shell Grapeshot Carcass Heated shot (a.k.a. hot shot) FIGURE 41—EIGHTEENTH CENTURY PROJECTILES. (Not to scale) Round shot was very useful for knocking out enemy batteries. The gunner put his cannon on the flank of the hostile guns and used ricochet firing so that the ball, just clearing the defense wall, would bounce among the enemy guns, wound the crews, and break the gun carriages. In the destruction of fort walls, shot was essential. After dismounting the enemy pieces, the siege guns moved close enough to batter down the walls. The procedure was not as haphazard as it sounds. Cannon were brought as close as possible to the target, and the gunner literally cut out a low section with gunfire so that the wall above tumbled down into the moat and made a ramp up to the breach. Firing at the upper part of the wall defeated its own purpose, for the rubble brought down only protected the foundation area, and the breach was so high that assault troops had to use ladders. The most effective bombardment of Castillo de San Marcos occurred during the 1740 siege, and shot did the most damage. The heaviest British siege cannon were 18-pounders, over 1,000 yards from the fort. Spanish Engineer Pedro Ruiz de Olano reported that the balls did not penetrate the massive main walls more than a foot and a half, but the parapets, being only 3 feet thick, suffered considerable damage. Some of the old parapets, Engineer Ruiz said, "have been demolished, and the new ones have suffered very much owing to their recent construction." (He meant that the new mortar had not sufficiently hardened.) Ruiz was not deceived about what would happen if hostile batteries were able to get closer; in such case, he thought, the enemy "will no doubt succeed in destroying the parapets and dismounting the guns." Variations of round shot were bar shot and chain shot (fig. 41), two or more projectiles linked together for simultaneous firing. Bar shot appears in a Castillo inventory of 1706, and like chain shot, was for specialized work like cutting a ship's rigging. There is one apocryphal tale, however, about an experiment with chain shot as anti-personnel missiles: instead of charging a single cannon with the two balls, two guns were used, side by side. The ball in one gun was chained to the ball in the other. The projectiles were to fly forth, stretching the long chain between them, mowing down a sizeable segment of the enemy. Instead, the chain wrapped the gun crews in a murderous embrace; one gun had fired late.

[Dept of PMM Artists & things]

Cannon Fuzes

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The eighteenth century fuze was a wooden tube several inches long, with a powder composition tamped into its hole much like the nineteenth century fuze (fig. 42c). The hole was only a quarter of an inch in diameter, but the head of the fuze was hollowed out like a cup, and "mealed" (fine) powder, moistened with "spirits of wine" (alcohol), was pressed into the hollow to make a larger igniting surface. To time the fuze, a cannoneer cut the cylinder at the proper length with his fuze-saw, or drilled a small hole (G) where the fire could flash out at the right time. Some English fuzes at this period were also made by drawing two strands of a quickmatch into the hole, instead of filling it with powder composition. The ends of the match were crossed into a sort of rosette at the head of the fuze. Paper caps to protect the powder composition covered the heads of these fuzes and had to be removed before the shell was put into the gun. FIGURE 42—NINETEENTH CENTURY PROJECTILE FUZES. a—Cross-section of Bormann fuze. b—Top of Bormann fuze. c—Wooden fuze for spherical shell. d—Wood-and-paper fuze for spherical shell. e—Percussion fuze. Bombs were not filled with powder very long before use, and fuzes were not put into the projectiles until the time of firing. To force the fuze into the hole of the shell, the cannoneer covered the fuze head with tow, put a fuze-setter on it, and hammered the setter with a mallet, "drifting" the fuze until the head stuck out of the shell only 2/10 of an inch. If the fuze had to be withdrawn, there was a fuze extractor for the job. This tool gripped the fuze head tightly, and turning a screw slowly pulled out the fuze. The conical paper-case fuze (fig. 42d), inserted in a metal or wooden plug that fitted the fuze hole, contained composition whose rate of burning was shown by the color of the paper. A black fuze burned an inch every 2 seconds. Red burned 3 seconds, green 4, and yellow 5 seconds per inch. Paper fuzes were 2 inches long, and could be cut shorter if necessary. Since firing a shell from a 24-pounder to burst at 2,000 yards meant a time flight of 6 seconds, a red fuze would serve without cutting, or a green fuze could be cut to 1-1/2 inches. Sea-coast fuzes of similar type were used in the 15-inch Rodmans until these big smoothbores were finally discarded sometime after 1900. The Bormann fuze (fig. 42a), the quickest of the oldtimers to set, was used for many years by the U.S. Field Artillery in spherical shell and shrapnel. Its pewter case, which screwed into the shell, contained a time ring of powder composition (A). Over this ring the top of the fuze case was marked in seconds. To set the fuze, the gunner merely had to cut the case at the proper mark—at four for 4 seconds, three for 3 seconds, and so on—to expose the ring of powder to the powder blast of the gun. The ring burned until it reached the zero end and set off the fine powder in the center of the case; the powder flash then blew out a tin plate in the bottom of the fuze and ignited the shell charge. Its short burning time (about 6 seconds) made the Bormann fuze obsolete as field gun ranges increased. The main trouble with this fuze, however, was that it did not always ignite! ! The percussion fuze was an extremely important development of the nineteenth century, particularly for the long-range rifles. The shock of impact caused this fuze to explode the shell at almost the instant of striking. Percussion fuzes were made in two general types: the front fuze, for the nose of an elongated projectile; and the base fuze, at the center of the projectile base. The base fuze was used with armor-piercing projectiles where it was desirable to have the shell penetrate the target for some distance before bursting. Both types were built on the same principles. A Hotchkiss front percussion fuze (fig. 42e) had a brass case which screwed into the shell. Inside the case was a plunger (A) containing a priming charge of powder, topped with a cap of fulminate. A brass wire at the base of the plunger was a safety device to keep the cap away from a sharp point at the top of the fuze until the shell struck the target. When the gun was fired, the shock of discharge dropped a lead plug (B) from the base of the fuze into the projectile cavity, permitting the plunger to drop to the bottom of the fuze and rest there, held by the spread wire, while the shell was in flight. Upon impact, the plunger was thrown forward, the cap struck the point and ignited the priming charge, which in turn fired the bursting charge of the shell.

[Dept of PMM Artists & things]

Scatter Projectiles

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When one of our progenitors wrathfully seized a handful of pebbles and flung them at the flock of birds in his garden, he discovered the principle of the scatter projectile. Perhaps its simplest application was in the stone mortar (fig. 43). For this weapon, round stones about the size of a man's fist (and, by 1750, hand grenades) were dumped into a two-handled basket and let down into the bore. This primitive charge was used at close range against personnel in a fortification, where the effect of the descending projectiles would be uncommonly like a short but severe barrage of over-sized hailstones. There were 6,000 stones in the ammunition inventory for Castillo de San Marcos in 1707. FIGURE 43—SPANISH 16-INCH PEDRERO (1788). This mortar fired baskets of stones. One of the earliest kinds of scatter projectiles was case shot, or canister, used at Constantinople in 1453. The name comes from its case, or can, usually metal, which was filled with scrap, musket balls, or slugs (fig. 41). Somewhat similar, but with larger iron balls and no metal case, was grape shot, so-called from the grape-like appearance of the clustered balls. A stand of grape in the 1700's consisted of a wooden disk at the base of a short wooden rod that served as the core around which the balls stood (fig. 41). The whole assembly was bagged in cloth and reinforced with a net of heavy cord. In later years grape was made by bagging two or three tiers of balls, each tier separated by an iron disk. Grape could disable men at almost 900 yards and was much used during the 1700's. Eventually, it was almost replaced by case shot, which was more effective at shorter ranges (400 to 700 yards). Incidentally, there were 2,000 sacks of grape at the Castillo in 1740, more than any other type projectile. Spherical case shot (fig. 41) was an attempt to carry the effectiveness of grape and canister beyond its previous range, by means of a bursting shell. It was the forerunner of the shrapnel used so much in World War I and was invented by Lt. Henry Shrapnel, of the British Army, in 1784. There had been previous attempts to produce a projectile of this kind, such as the German Zimmerman's "hail shot" of 1573—case shot with a bursting charge and a primitive time fuze—but Shrapnel's invention was the first air-bursting case shot which, in technical words, "imparted directional velocity" to the bullets it contained. Shrapnel's new shell was first used against the French in 1808, but was not called by its inventor's name until 1852.

[Dept of PMM Artists & things]

Cannon Incendiaries
& Chemical Projectiles

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Incendiary missiles, such as buckets or barrels filled with a fiercely burning composition, had been used from earliest times, long before cannon. These crude incendiaries survived through the 1700's as, for instance, the flaming cargoes of fire ships that were sent amidst the enemy fleet. But in the year 1672 there appeared an iron shell called a carcass (fig. 41), filled with pitch and other materials that burned at intense heat for about 8 minutes. The flame escaped through vents, three to five in number, around the fuze hole of the shell. The carcass was standard ammunition until smoothbores went out of use. The United States ordnance manual of 1861 lists carcasses for 12-, 18-, 24-, 32-, and 42-pounder guns as well as 8-, 10-, and 13-inch mortars. During the late 1500's, the heating of iron cannon balls to serve as incendiaries was suggested, but not for another 200 years was the idea successfully carried out. Hot shot was nothing but round shot, heated to a red glow over a grate or in a furnace. It was fired from cannon at such inflammable targets as wooden ships or powder magazines. During the siege of Gibraltar in 1782, the British fired and destroyed a part of Spain's fleet with hot shot; and in United States seacoast forts shot furnaces were standard equipment during the first half of the 1800's. The little shot furnace at Castillo de San Marcos National Monument was built during the 1840's; a giant furnace of the mid-1860's still remains at Fort Jefferson National Monument. Loading hot shot was not particularly dangerous. After the powder charge was in the gun with a dry wad in front of it, another wad of wet straw, or clay, was put into the barrel. When the cherry-red shot was rammed home, the wet wad prevented a premature explosion of the charge. According to the Ordnance Manual, the shot could cool in the gun without setting off the charge! Hot shot was superseded, about 1850, by Martin's shell, filled with molten iron. The smoke shell appeared in 1681, but was never extensively used. Similarly, a form of gas projectile, called a "stink shell," was invented by a Confederate officer during the Civil War. Because of its "inhumanity," and probably because it was not thought valuable enough to offset its propaganda value to the enemy, it was not popular. These were the beginnings of the modem chemical shells. In connection with chemical warfare, it is of interest to review the Hussite siege of Castle Karlstein, near Prague, in the first quarter of the fifteenth century. The Hussites emplaced 46 small cannon, 5 large cannon, and 5 catapults. The big guns would shoot once or twice a day, and the little ones from six to a dozen rounds. Marble pillars from Prague churches furnished the cannonballs. Many projectiles for the catapults, however, were rotting carcasses and other filth, hurled over the castle walls to cause disease and break the morale of the besieged. But the intrepid defenders neutralized these "chemical bursts" with lime and arsenic. After firing 10,930 cannonballs, 932 stone fragments, 13 fire barrels, and 1,822 tons of filth, the Hussites gave up.

[Dept of PMM Artists & things]

Fixed Ammunition
for Cannon

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In early days, due partly to the roughly made balls, wads were very important as a means of confining the powder and increasing its efficiency. Wads could be made of almost any suitable material at hand, but perhaps straw or hay ones were most common. The hay was first twisted into a 1-inch rope, then a length of the rope was folded together several times and finally rolled up into a short cylinder, a little larger than the bore. After the handier sabots came into use, however, wads were needed only to keep the ball from rolling out when the muzzle was down, or for hot shot firing. Gunners early began to consolidate ammunition for easier and quicker loading. For instance, after the powder charge was placed in a bag, the next logical step was to attach the wad and the cannonball to it, so that loading could be made in one simple operation—pushing the single round into the bore (fig. 48). Toward that end, the sabot or "shoe" (fig. 41) took the place of the wad. The sabot was a wooden disk about the same diameter as the shot. It was secured to the ball with a pair of metal straps to make "semi-fixed" ammunition; then, if the neck of the powder bag were tied around the sabot, the result was one cartridge, containing powder, sabot, and ball, called "fixed" ammunition. Fixed ammunition was usual for the lighter field pieces by the end of the 1700's, while the bigger guns used "semi-fixed." In transportation, cartridges were protected by cylinders and caps of strong paper. Sabots were sometimes made of paper, too, or of compressed wood chips, to eliminate the danger of a heavy, unbroken sabot falling amongst friendly troops. A big mortar sabot was a lethal projectile in itself!

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[Dept of PMM Artists & things]

Rockets

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Today's rocket projectiles are not exactly new inventions. About the time of artillery's beginning, the military fireworker came into the business of providing pyrotechnic engines of war; later, his job included the spectacular fireworks that were set off in celebration of victory or peace. Artillery manuals of very early date include chapters on the manufacture and use of fireworks. But in making war rockets there was no marked progress until the late eighteenth century. About 1780, the British Army in India watched the Orientals use them; and within the next quarter century William Congreve, who set about the task of producing a rocket that would carry an incendiary or explosive charge as far as 2 miles, had achieved such promising results that English boats fired rocket salvos against Boulogne in 1806. The British Field Rocket Brigade used rockets effectively at Leipzig in 1812—the first time they appeared in European land warfare. They were used again 2 years later at Waterloo. The warheads of such rockets were cast iron, filled with black powder and fitted with percussion fuzes. They were fired from trough-like launching stands, which were adjustable for elevation. Rockets seem to have had a demoralizing effect upon untrained troops, and perhaps their use by the British against raw American levies at Bladenburg, in 1814, contributed to the rout of the United States forces and the capture of Washington. They also helped to inspire Francis Scott Key. Whether or not he understands the technical characteristics of the rocket, every schoolboy remembers the "rocket's red glare" of the National Anthem, wherein Key recorded his eyewitness account of the bombardment of Fort McHenry. The U.S. Army in Mexico (1846-48) included a rocket battery, and, indeed, war rockets were an important part of artillery resources until the rapid progress of gunnery in the latter 1800's made them obsolescent.