Technical Report—Shot to Shrapnel-and Back

Solid round shot was the standard U. S. Navy projectile during the Revolutionary War and the War of 1812. But experiments with explosive shells and increasing construction of iron ships changed ship magazines significantly by the time of the Civil War.

Non-explosive Projectiles

For approximately 100 years, the U. S. Navy’s basic weapon at sea was the smooth-bore, muzzle-loading cannon. The standard projectile for early muzzle- loaders was solid round shot, known simply as “shot.” The first shot was probably made of stone. Although cheaper than metal shot, stone shot was soon rejected as too light and brittle. Iron, bronze, and lead shot were all in use by the mid-14th century. By 1400, the French were making shot of cast iron, and by the time of the American Revolutionary War virtually all round shot was cast iron.¹

Shot was cast from soft iron; hard iron tended to break up on impact with the target, rather than penetrating. Shot molds were made of both iron and sand. U. S. Navy contracts during the War of 1812 specified that shot was to be cast in iron molds; but by 1819 there was a bonus paid for using sand molds; and by 1842 the Navy specified that shot be cast in sand.² Sand molds produced more spherical shot, without the cavities that resulted from iron molds. Mold models consisted of two hemispheres of polished copper, which, by means of a groove in one and a lip in the other, fitted together to form a perfect sphere.

After casting—and periodically thereafter—shot was inspected for uniformity and defects. Shot with cavities exceeding 0.1 inch were rejected. The shot also had to pass in all directions through a large gauge ring not less than four calibers long. Less variance was allowed as time went on: in 1845, shot could vary as much as 0.06 of an inch; later it was 0.03; and after 1852 it was 0.02.³

Shot was also rejected if it was lighter than 1/32 of its caliber weight. Shot was supposed to match its designated weight— such as 18-, 24-, or 32-pounder—but this was not always the case. During the War of 1812, U. S. shot was lighter than British shot, probably because of the density of the iron. In 1856, the average weight of a 32-pounder shot was 32.5 pounds, while that of a 64-pounder was 63.75 pounds.⁴

Shot was supposed to be lacquered, greased, or painted, and care was to be taken to ensure that shot stored in the shot racks (“garlands”) near the guns was always clean. If possible, shot stored below was placed where there was free circulation of air. The largest rust accumulations were in the shot lockers, which were usually under the main hatch. Thus, whenever it rained or the deck was washed down, the shot got wet. After returning from a cruise, it was not unusual to find the shot in the lockers rusted together. A lack of suitable shot storage sheds at the naval yards was also a constant problem. Rust damage greatly reduced shot accuracy, and large accumulations might prevent shot from fitting into the bore of a gun. Even a small accumulation of rust could affect windage.

In an engagement, shot was fired to hole an enemy ship near the waterline and thus sink it, to destroy masts and spars, and to inflict crew casualties. But wooden ships had hulls of stout oak that could sustain a tremendous amount of punishment. Even if shot penetrated the wooden hull, it might leave only a small hole on the outside because the wood fibers would close back again after the shot had passed through. The hole would also have to be near the waterline to sink the ship. Generally, a good plug could contain the damage. Thus, many hits were required to hole a ship sufficiently to sink it, especially because shot striking the water would lose much of its force. The sloping surfaces of a vessel could further dissipate that force.

Large frigates and ships-of-the-line were rarely sunk in battle. They could take a tremendous battering—even by large caliber guns in lengthy engagements. In one battle in 1800, a British 74, the Foudroyant, fired 2,758 shot at close range at a French line-of-battle ship, the Guillaume Tell, before the latter struck her colors—and two other British ships had been firing at the French vessel at the same time. Even so, the Guillaume Tell was not damaged enough to preclude its incorporation into the Royal Navy soon afterward.⁵

Most ships were not sunk, but disabled by damage to masts and spars or crew casualties and then captured. The antipersonnel effects of shot occurred on the egress of the shot from the wood. The effects of splintering and damage were greatest when the force of the shot was only slightly more than required to pass through the wood.

Hot shot was designed to set wooden sailing ships on fire. Ordinary round shot was heated red-hot (white-hot shot might be too brittle). The powder charge—in a strong flannel cartridge with no holes— was loaded in the gun, followed by a tight clay wad or a wet hay wad with the water squeezed out. The hot shot was then loaded into the gun by means of a carrier, and the gun was fired. If the gun was to be fired depressed, another tight wet wad was rammed in to hold the shot in place. If two wads were used—one dry and one damp—there was no danger of ignition by the shot, and the gun could be pointed before it was fired.

When firing hot shot, a reduced powder charge was used, usually from one- quarter to one-sixth the weight of the shot; by the mid-19th century, the normal charge for a shot was one-third its weight. This enabled the shot to penetrate the enemy ship’s hull, but not more than 10-12 inches, to allow for sufficient air for combustion. Some ships sank as the result of explosions caused by hot shot igniting powder and magazines.

Bar and chain shot, also known as “dismantling shot,” were employed at sea from early times. They were especially useful against an enemy ship’s rigging—particularly in chase. However, such shot was so inaccurate that it often had little or no Chain shot effect, as in the engagement between the USS Constitution and HMS Java in 1812.

Double-headed shot (also called “bar- shot” or “stang-balls”) consisted of two solid hemispheres or two round shot connected by a bar 8-14 inches long. Chain shot consisted of two round shot connected by a chain eight or more inches long. There were many other types of dismantling shot, including expanding- shot and star-shot. The latter was fired from the President while she was being chased by the British ship Endymion in the War of 1812; one destroyed a substantial portion of the Endymion's foresail. However, double-headed shot had only about two-thirds the range of round shot fired at the same elevation and charge.

Grapeshot was in use by the 14th century. At first, it was merely a canvas cartridge, sack, or net containing small balls. Later it consisted of an iron plate, from the center of which passed up an iron spindle —the whole being known as a stool. Around the stool were placed small round shot enclosed in a canvas bag, which was drawn together by strong line; this was later referred to as quilted shot. Individual shot varied according to the size of the gun— weighing from eight ounces to four pounds. But the whole weighed about the same as a single ordinary round shot. The name grapeshot derived from the fact that the finished article looked very much like a bunch of grapes. When the gun was fired, the shock of the discharge broke the cloth and scattered the balls, much like a modern shotgun.

Because the quilting around the balls tended to deteriorate rapidly from the effects of the iron, it was replaced in the 1850s by tier shot, a technique that originated in France. An iron pin, secured by a nut at the end, ran through a series of flat iron plates with holes to hold the shot. There was a tier of shot between each two plates, hence the name. The number of tier shot balls was less than the old grapeshot, but their individual weight was greater. There were three shot to each tier, for a total of nine. Tier shot was more durable and ultimately cheaper, because there was no quilting to be replaced. Tier grapeshot had more spread in flight than the old quilted shot.

During the Civil War, some tier shot had only two plates—top and bottom— with rings of circular section for the two intermediate plates. The balls of each tier thus nestled into those of the next, substantially lightening and shortening the stand. The number of tiers also varied: some Confederate grape had seven or more.

Grapeshot was used only at relatively close range. The U. S. Navy Ordnance Instructions of 1860 called for grapeshot to be employed against warships out to 150 yards. It could be used against men on the spar (open) deck of an enemy ship at ranges of 200-300 yards; and it could be used at 400 yards (a double stand at 300 yards) against light ships, boats, or masses of men, because the dispersion of the balls at that distance was about 30 yards.⁶ Grapeshot was not used much at sea, except against exposed decks or beaches. But it was useful against rigging.

Even smaller than grape was case shot, also known as “canister,” “cannister,” or “common case.” It was an improvement over what was called “langrage” in the U. S. Navy (also “langrel” and “langridge”). Langrage could be stones, nails, bolts, flints, or bits of scrap fired from cannon. Canister or case shot consisted of a cylinder or case or iron or tin, with tops and bottoms of wood or iron. The cylinder was packed with pieces of small shot or bullets of different sizes, or loose iron or pebbles; the interstices were filled with shavings or sawdust. One contemporary British writer complained that canister shot fired by the U. S. frigate Chesapeake during the War of 1812 consisted of angular and jagged pieces of iron, broken gunlocks, and copper nails.⁷

Case shot produced a denser pattern than grape. It was intended for antipersonnel use against massed troops on land or in boats, and for destroying the rigging of ships. However, it was effective only at short ranges owing to the rapid dispersion and light weight of the balls. But the number of projectiles enabled case to have a greater effect at short range than any other projectile, including grape. Case was not used at ranges of more than 300-500 yards.

Canister was particularly favored for the shot guns known as carronades. In 1799, when James and Ebenezer Watson —Navy Agents at New York—were asked to secure some imported 32- pounder carronades for the frigate United States, they were also told to purchase 50 rounds for each gun—half to be round shot and the other half canister.⁸

More than one shot could be fired at the same time. Double shot usually consisted of two round shot or round and grape shot together, the round shot being loaded first. Double-shotting, however, put a strain on the carriage, breeching, and tackles; the increased recoil slowed servicing of the gun. Thus, double-shotting was forbidden without express orders from the captain of the vessel. Triple- shotting was even less efficient; it was used only for close action and only for the first broadside.

If double-shotted, a gun was fired with a reduced powder charge. A wad might be placed between the two shot, the idea being to reduce the possibility of the shot striking one another and breaking. By the time of the Civil War, this was no longer practiced; it was thought that without the wad the shot would move together in flight.

Double-shotting was used against boats or troops on shore, especially in ricochet, but firing this way was even less accurate than with one shot, and two shot had considerably less velocity. In 1850, a 32-pounder shot fired double-shotted could not penetrate 30 inches of oak (the hull of a line-of-battle ship) at more than 100 yards range. At 500 yards, the double shot might penetrate only 18 inches.⁹

In 1836, John Rodgers of the Board of Navy Commissioners recommended that double-shotting not be used in carronades “excepting where the vessels are very nearly in contact” and from long guns “only when near, as the shot generally separate so widely after leaving the gun that the chance of their striking the object is small.”¹⁰

By 1851, double-shotting was not practiced by the U. S. Navy even at 400 yards range by guns smaller than 32- pounders, and never with 32-pounders of less than 46 hundredweight (5,152 pounds).¹¹ By the Civil War, double- shotting was recommended by the U. S. Navy only at ranges closer than 300 yards from heavy 32-pounders of 46 hundredweight and greater. For lighter 32-pounders, the range for double-shotting was not to exceed 200 yards.¹²

The allowances of shot per gun varied greatly, both in types and numbers, according to the length of time and purpose for which the vessel was at sea. A general rule for the U. S. Navy—before the advent of explosive shell—was 100 rounds per gun with three-quarters of these in ordinary round shot. For example, ordnance supplies ordered in August 1798 for the new 18-gun brig Norfolk included 18 six-pounder guns, 1,350 round shot (75 per gun), and 450 stands of grape (25 per gun). In April 1799, among the supplies for the frigate John Adams, which was armed with 24 12-pounders, were 1,600 round shot, 400 stands of grape, and 400 double-headed shot.¹³

Incendiary and Explosive Projectiles

In addition to solid shot, muzzle-loading cannon were capable of firing incendiary and explosive projectiles. Incendiary devices were not new at sea: the ancient Greeks used “fire pots” filled with incendiary compositions. But incendiaries thrown by guns at sea were first used in the second half of the 17th century..¹⁴

Incendiary projectiles were known as “carcasses.” These were essentially shells—hollow concentric spheres made of cast iron—with vents equally spaced around the middle. The shell was packed with an incendiary mix that would be difficult to extinguish. In 1815, one Royal Navy composition called for two parts pitch, four parts saltpeter, one part sulphur, and three parts corned powder.¹⁵ By the mid-19th century, the U. S. Navy mix consisted of white turpentine, spirits of white turpentine, and port-fire composition. Wooden sticks were used to poke holes from the vents through this composition to the center of the shell. Three strands of quick-match were inserted in the holes, long enough to allow several inches to be folded over the edge of the holes. Dry port-fire composition was pressed into the vents to keep the quick- match in place.

Carcass shells burned for eight to ten minutes; they were designed to set fire to their surroundings through the vents. In 1815, one writer described a Royal Navy carcass shell in these words: “It spreads a flame in three distinct openings, which is so strong that the fire extends a full yard in length from the ball itself, and is so powerful that any thing under, over, or near, cannot escape its effects.”¹⁶

Mortars had long been used for projecting explosive shell, but experiments using long guns had not been successful. It was not until the end of the 18th century, during the siege of Gibraltar from 1779 to 1783, that shell was used successfully with long guns. During the siege. Captain Mercier of the British Army suggested that 5.5-inch mortar shell be fired with short fuze from 24- pounder long guns of the same caliber. In a trial on 25 September 1779, the short fuzes often burst the shells over the Spanish troops as intended.¹⁷

Mercier’s improvised system worked well enough, but it was greatly improved by Lieutenant (later Major-General) Henry Shrapnel of the Royal Artillery. In 1784, he invented what he called “spherical case,” consisting of a hollow iron shell with a fuze and a number of spherical lead musket balls surrounding a small charge of powder. The fuze was cut to ignite the charge over the target. The charge was just enough to open the shell, and hence not enough to scatter the shot, which continued in the original line of (light.

Shrapnel’s invention was disregarded for 20 years. It was not until 1804, during the Napoleonic Wars, that it was given a trial, and subsequently was adopted by the British Ordnance Committee.¹⁸

Shrapqel shells were thinner than other shell and had to be carefully cast. Their weight empty was about half that of solid shot of the same caliber, but with the lead balls added they weighed almost as much as their comparable solid shot, lead being more dense than iron.

The technique of loading shrapnel shell changed by the mid-19th century. Instead of putting the balls in and then adding the powder to fill the empty spaces between them, the powder was confined to a chamber. This prevented it from being crushed by friction and allowed a reduction in the bursting charge.

In U. S. Navy practice, the proper number of balls was inserted into the shell, and then a grooved mandril was pushed through them to the other side of the shell. Melted sulphur was then poured through the fuze hole, entering the case through the grooves in the mandril. When the sulphur cooled, the mandril was withdrawn and the resulting chamber was ready to receive the bursting charge. If a mandril was not employed, melted sulphur was still used; after it cooled, it was bored out at the top (along with any of the balls) to receive the charge. This separated the charge from the bullets and enabled the loaded shell to be transported safely. In addition, the powder was concentrated and the explosion more powerful; as a result, the amount of powder could be reduced.

Shrapnel was employed at the range where grape became ineffective. Its effects could be devastating, much like grapeshot at short range. It was used against troops on shore or against ships in which a number of men could be seen on the exposed decks.

Explosive shell, as distinct from shrapnel, did not come into its own until the mid-19th century. Explosive shells were hollow, concentric, cast-iron spheres with a fuze hole. The fuze would explode the bursting charge inside the shell. Shells were used at sea to destroy material and men; the smoke from the blast in a confined space on board ship would greatly inhibit an enemy crew as well.

The Chinese may have used shells as early as the 12th or 13th century. The first shells were probably thrown by hand or by slings (by “grenadiers”). Hand- grenades were kept on board ships through the Civil War.

There are numerous reports of shell being used in sieges during the 15th and 16th centuries. Voltaire wrote that shells (“bombs”) were first used at sea by the French in their bombardment of Algiers in 1681. The Russians destroyed a Turkish fleet in the Battle of Liman in 1788 with the use of shells.¹⁹

Even before the advent of iron ship construction, there were compelling arguments for the use of shell. Shot was effective (below decks, at any rate) only when it passed through the wood of the hull, but far too frequently this penetration did not occur. Iron ship construction, which was beginning in the early 19th century, meant that, in time, hulls would be nearly impervious to shot.

The purpose of the shell was to lodge itself in its target, then explode. The structure of a ship could be much more effectively damaged by shell than shot, and the explosion of a large shell in the side of a ship could produce a hole large enough to sink her. In a September 1852 trial of shell fired from a IX-inch Dahlgren gun, the shell’s explosion displaced 27 cubic feet of a target of white oak 30 feet thick from 1,300 yards range.²⁰ Shot might have greater accuracy and range, but shell was much more destructive.

The French took the lead in using shell, quite simply because they had less to lose and more to gain than the British from the introduction of a new system. The disadvantage of having fewer ships could be offset by having superior ordnance. In 1837, the French incorporated a shell gun designed by Colonel Henri Paixhans in all of their ship batteries.

Shells were used by the U. S. Navy in the War of 1812, and immediately after the war there were a number of experiments with new types. But it was not until the gunnery experiments begun in 1839 at Sandy Hook and on board the steamer Fulton II—which included Paixhans-type guns, hollow shot, solid shot, and explosive shell—that the superiority of the new shell gun was conclusively demonstrated. By the 1840s, shell guns were a part of standard U. S. Navy ship armament.

Seamen and officers alike were apprehensive about the new shells and shell guns. Lieutenant John Dahlgren, perhaps the most enthusiastic shell advocate in the U. S. Navy, noted in his diary:

“I had the opportunity of firing the first shot from the ‘Cumberland.’ There are four Paixhans, or shell guns, in the ship, and these have been assigned to my division. The Captain gave me orders to fire a shell from each piece. Accordingly I had the heavy 68-pound shot drawn and the shells substituted. ... It was amusing to-day, when about to fire, to notice that the crew had left the gun, as if desirous of avoiding any accident from the shell, which is new to them and seems alarming. I at once ordered them to stand to their quarters in their proper places at the gun. Shot they do not mind, but shell they dread.²¹”

In the earliest use of shells, the shell fuze was lit first and then the main charge to the gun. Fuzes were known to be dangerously erratic; as a result, gunners greatly feared shells. The French continued this practice longer than the British and Americans, who placed the shell with the fuze positioned toward the muzzle along the axis of the bore (“up and out”), so that the fire from the discharge of the mortar or gun would automatically light the fuze.

Wood bottoms, known as “sabots” (wooden shoes, in French), were eventually used both with explosive shell and spherical case for long guns, but not in mortars. The sabot was a piece of light, coarse-grained wood turned in a lathe to a diameter slightly less than that of the shell and tapered to fit the slope of the bore in the chambered shell guns. The sabot ensured that the fuze was kept in the proper position toward the muzzle of the gun. (If the shell somehow turned around in the bore, the discharge of the gun might drive the fuze in and explode the shell before it left the barrel.) The sabot was held in place on the shell by two tin straps. The sabot could also be used with round shot, which would then not roll about on the deck. It took the place of the wad, which might prevent the fuze from being lit. Wad was not used over the top of the shell unless there was heavy rolling and then only a light wad was used. Despite all these precautions, there were many problems with the early shells, particularly premature bursting.

Shells could be fired in combination with other rounds, but this was not often practiced. A shell and a solid shot might be double-shotted, but two shells were never fired together.

The fuze ignited the explosive charge in the shell and also determined the time of the explosion. The earliest fuzes were made of paper, wood, and iron. The fuze was essentially a tapered plug. A hole ran its length to within a short distance of the small end and was filled with a composition of gunpowder, sulphur, and saltpeter usually predetermined to burn between four and five seconds.

The early fuzes were ribbed, each rib representing a fraction of burning time. The fuze was cut with a hand saw for the desired burn time and the remainder discarded. The cut fuze was then driven into the shell with a wooden mallet.

Wooden fuzes tended to deteriorate in the damp, hot conditions on board ship and were subject to accidental discharge. This led to experimentation with different types of fuzes, including copper screw fuzes of different lengths; protective metal caps were kept in place until the fuze was placed in the gun. The cap protected the fuze—and hence the shell— against accidental discharge.

By the 1850s, wooden fuzes had been replaced by metal fuzes. By the Civil War, U. S. Navy fuzes were made of copper and tin.

Another advantage of the metal fuze was that it better withstood bending. To prevent the fuze composition from reacting with the metal case, the composition was first put into a paper case and inserted into the metal when the fuze was ready to be used. The metal fuze did not extend much into the shell—the eight- inch shell did not extend past the metal of the shell casing.

By the time of the Civil War, U. S. Navy shell fuzes came with 5-, 10-, and 15-second bum times. The 5-second fuze was to be used—with ordinary charges— at ranges up to 1,320 yards; the 10- second fuze was for 1,320-2,400 yards for the 8-inch and 32-pounder (2,000 yards for the IX-inch gun) with distant firing charges. The 15-second fuze had a range —with distant firing charges, of 3,080 yards from 32-pounder and 8-inch guns. Half the fuzes for the large guns on board ship were to be 5-seconds, 32-pdr shell one-quarter were to be 10-seconds, and the remaining quarter were 15- seconds.²²

At the same time, a great variety of new fuzes appeared worldwide. The superior Bormann fuze, invented by Captain Bormann of the Belgian Army, was first used by the U. S. Navy in boat howitzer shells. The concussion fuze, set in action by the shock of discharge, and the percussion fuze, set off by impact with the target, were invented in the 1840s and 1850s. During the Civil War. percussion fuzes were used on board U. S. Navy ships.

Shell diameters were the same as shot diameters of like caliber. The thickness of the shell casing ranged from 0.8 of an inch for the 18-pounder to 1.5 inches for an eight-inch and 1.8 inches for the ten- inch shell. Fuze holes were all 0.6 of an inch by the time of the Civil War, and the metal at the fuze hole was reinforced to support the fuze firmly. In the early shells, there was another small hole in the carcass of the shell to allow it to be filled with powder once the fuze was put in.

Before filling the shell with powder on board ship, the shell was secured to its sabot by tin straps and examined to see that it was clean and dry inside and out. The powder was inserted with a funnel.

The fuze was then carefully screwed in place with a fuze wrench. Loaded shells were marked with red paint and placed in red boxes. The length of the fuze was painted on the box in black. Loaded shells were to be inspected periodically.

By 1850, the U. S. Navy had copied French practice and added a lead patch over the fuze. This was removed by the loader, who showed it to the gun captain as proof that the fuze was uncovered. This was not done until the shell was actually in the bore of the gun. Then the shell was pushed (not rammed) home.

By the time of the Civil War, only one shell, kept in its box, was allowed at the gun, compared to ten rounds for each of the shot guns. The shell was stored between the trucks (wheels) on the port side of the gun. In contrast with Royal Navy practice, no extra shells were allowed on the deck during an action. To ensure that this rule was followed, no shells were to be supplied from the magazine unless an empty box was first presented as proof that the last shell was already in the gun.

Shells were stored apart from the magazines in special shell rooms. On ships armed entirely with shell guns, there were two or more shell rooms. The danger of fire led to the recommendation that the shell rooms be located, at their highest point, no less than six feet below the waterline.

By 1861, shells were available for service guns in the U. S. Navy as follows:²³

	Weight (fuzed and saboted)	Bursting charge
12-pdr boat horwitzer		.5
24-pdr boat howitzer
18-pdr gun	12
24-pdr gun	16
32-pdr gun	26.5	.9
42-pdr	35
VII-inch shell gun	52.75	1.85
IX-inch shell gun	73.5	3.0
X-inch shell gun	101.5	4.0
XI-inch shell gun	135.5	6.0

 

By the Civil War, experiments with rifling and elongated projectiles were increasing. Rifles designed by Robert P. Parrott and Dahlgren did see service on board ship during the war, but the basic workhorse of both the Union and Confederate navies was the smoothbore gun firing round shot and shells. Ironically, the shells—so effective against wooden vessels—were not as successful against the new ironclads. The heavy shell gun, firing solid shot, proved to be the most effective weapon against them.