The Change into Modern Artillery
With Rodman’s gun, the muzzle-loading smoothbore was at the apex of its development. Through the years great progress had been made in mobility, organization, and tactics. Now a new era was beginning, wherein artillery surpassed even the decisive role it had under Gustavus Adolphus and Napoleon. In spite of new infantry weapons that forced cannon ever farther to the rear, artillery was to become so deadly that its fire caused over 75 percent of the battlefield casualties in World War I.
Many of the vital changes took place during the latter years of the 1800’s, as rifles replaced the smoothbores. Steel came into universal use for gun founding; breech and recoil mechanisms were perfected; smokeless powder and high explosives came into the picture. Hardly less important was the invention of more efficient sighting and laying mechanisms.
The changes did not come overnight. In Britain, after breechloaders had been in use almost a decade, the ordnance men went back to muzzle-loading rifles; faulty breech mechanisms caused too many accidents. Not until one of H.M.S. Thunderer’s guns was inadvertently double-loaded did the English return to an improved breechloader.
The steel breechloaders of the Prussians, firing two rounds a minute with a percussion shell that broke into about 30 fragments, did much to defeat the French (1870-71). At Sedan, the greatest artillery battle fought prior to 1914, the Prussians used 600 guns to smother the French army. So thoroughly did these guns do their work that the Germans annihilated the enemy at the cost of only 5 percent casualties. It was a demonstration of using great masses of guns, bringing them quickly into action to destroy the hostile artillery, then thoroughly “softening up” enemy resistance in preparation for the infantry attack. While the technical progress of the Prussian artillery was considerable, it was offset in large degree by the counter-development of field entrenchment.
As the technique of forging large masses of steel improved, most nations adopted built-up (reinforcing hoops over a steel tube) or wire-wrapped steel construction for their cannon. With the advent of the metal cartridge case and smokeless powder, rapid-fire guns came into use. The new powder, first used in the Russo-Turkish War (1877-78), did away with the thick white curtain of smoke that plagued the gunner’s aim, and thus opened the way for production of mechanisms to absorb recoil and return the gun automatically to firing position. Now, gunners did not have to lay the piece after every shot, and the rate of fire increased. Shields appeared on the gun—protection that would have been of little value in the days when gunners had to stand clear of a back-moving carriage.
During the early 1880’s the United States began work on a modern system of seacoast armament. An 8-inch breech-loading rifle was built in 1883, and the disappearing carriage, giving more protection to both gun and crew, was adopted in 1886. Only a few of the weapons were installed by 1898; but fortunately the overwhelming naval superiority of the United States helped bring the War with Spain to a quick close.
During this war, United States forces were equipped with a number of British 2.95-inch mountain rifles, which, incidentally, served as late as World War II in the pack artillery of the Philippine Scouts. Within the next few years the antiquated pieces such as the 3-inch wrought-iron rifle, the 4.2-inch Parrott siege gun, converted Rodmans, and the 15-inch Rodman smoothbore were finally pushed out of the picture by new steel guns. There were small-caliber rapid-fire guns of different types, a Hotchkiss 1.65-inch mountain rifle, and Hotchkiss and Gatling machine guns. The basic pieces in field artillery were 3.2- and 3.6-inch guns and a 3.6-inch mortar. Siege artillery included a 5-inch gun, 7-inch howitzers, and mortars. In seacoast batteries were 8-, 10-, 12-, 14-, and 16-inch guns and 12-inch mortars of the primary armament; intermediate rapid-fire guns of 4-, 4.72-, 5-, and 6-inch calibers; and 6- and 15-pounder rapid-fire guns in the secondary armament.
The Japanese showed the value of the French system of indirect laying (aiming at a target not visible to the gunner) during the Russo-Japanese War (1904-05). Meanwhile, the French 75-mm. gun of 1897, firing 6,000 yards, made all other field artillery cannon obsolete. In essence, artillery had assumed the modern form. The next changes were wrought by startling advances in motor transport, signal communications, chemical warfare, tanks, aviation, and mass production.
Black powder was used in all firearms until smokeless and other type propellants were invented in the latter 1800’s. “Black” powder (which was sometimes brown) is a mixture of about 75 parts saltpeter (potassium nitrate), 15 parts charcoal, and 10 parts sulphur by weight. It will explode because the mixture contains the necessary amount of oxygen for its own combustion. When it burns, it liberates smoky gases (mainly nitrogen and carbon dioxide) that occupy some 300 times as much space as the powder itself.
Early European powder “recipes” called for equal parts of the three ingredients, but gradually the amount of saltpeter was increased until Tartaglia reported the proportions to be 4-1-1. By the late 1700’s “common war powder” was made 6-1-1, and not until the next century was the formula refined to the 75-15-10 composition in majority use when the newer propellants arrived on the scene.
As the name suggests, this explosive was originally in the form of powder or dust. The primitive formula burned slowly and gave low pressures—fortunate characteristics in view of the barrel-stave construction of the early cannon. About 1450, however, powder makers began to “corn” the powder. That is, they formed it into larger grains, with a resulting increase in the velocity of the shot. It was “corned” in fine grains for small arms and coarse for cannon.
Making corned powder was fairly simple. The three ingredients were pulverized and mixed, then compressed into cakes which were cut into “corns” or grains. Rolling the grains in a barrel polished off the corners; removing the dust essentially completed the manufacture. It has always been difficult, however, to make powder twice alike and keep it in condition, two factors which helped greatly to make gunnery an “art” in the old days. Powder residue in the gun was especially troublesome, and a disk-like tool (fig. 44) was designed to scrape the bore. Artillerymen at Castillo de San Marcos complained that the “heavy” powder from Mexico was especially bad, for after a gun was fired a few times, the bore was so fouled that cannonballs would no longer fit. The gunners called loudly for better grade powder from Spain itself.
How much powder to use in a gun has been a moot question through the centuries. According to the Spaniard Collado in 1592, the proper yardstick was the amount of metal in the gun. A legitimate culverin, for instance, was “rich” enough in metal to take as much powder as the ball weighed. Thus, a 30-pounder culverin would get 30 pounds of powder. Since a 60-pounder battering cannon, however, had in proportion a third less metal than the culverin, the charge must also be reduced by a third—to 40 pounds!
Other factors had to be taken into account, such as whether the powder was coarse-or fine-grained; and a short gun got less powder than a long one. The bore length of a legitimate culverin, said Collado, was 30 calibers (30 times the bore diameter), so its powder charge was the same as the weight of the ball. If the gunner came across a culverin only 24 calibers long, he must load this piece with only 24/30 of the ball’s weight. Collado’s pasavolante had a tremendous length of some 40 calibers and fired a 6- or 7-pound lead ball. Because it had plenty of metal “to resist, and the length to burn” the powder, it was charged with the full weight of the ball in fine powder, or three-fourths as much with cannon powder. The lightest charge seems to have been for the pedrero, which fired a stone ball. Its charge was a third of the stone’s weight.
In later years, powder charges lessened for all guns. English velocity tables of the 1750’s show that a 9-pounder charged with 2-1/4 pounds of powder might produce its ball at a rate of 1,052 feet per second. By almost tripling the charge, the velocity would increase about half. But the increase did not mean the shot hit the target 50 percent harder, for the higher the velocity, the greater was the air resistance; or as Müller phrased it: “a great quantity of Powder does not always produce a greater effect.” Thus, from two-thirds the ball’s weight, standard charges dropped to one-third or even a quarter; and by the 1800’s they became even smaller. The United States manual of 1861 specified 6 to 8 pounds for a 24-pounder siege gun, depending on the range; a Columbiad firing 172-pound shot used only 20 pounds of powder. At Fort Sumter, Gillmore’s rifles firing 80-pound shells used 10 pounds of powder. The rotating band on the rifle shell, of course, stopped the gases that had slipped by the loose-fitting cannonball.
Black powder was, and is, both dangerous and unstable. Not only is it sensitive to flame or spark, but it absorbs moisture from the air. In other words, it was no easy matter to “keep your powder dry.” During the middle 1700’s, Spaniards on a Florida river outpost kept powder in glass bottles; earlier soldiers, fleeing into the humid forest before Sir Francis Drake, carried powder in peruleras—stoppered, narrow-necked pitchers.
As for magazines, a dry magazine was just about as important as a shell-proof one. Charcoal and chloride of lime, hung in containers near the ceiling, were early used as dehydrators, and in the eighteenth century standard English practice was to build the floor 2 feet off the ground and lay stone chips or “dry sea coals” under the flooring. Side walls had air holes for ventilation, but screened to prevent the enemy from letting in some small animal with fire tied to his tail. Powder casks were laid on their sides and periodically rolled to a different position; “otherwise,” explains a contemporary expert, “the salt petre, being the heaviest ingredient, will descend into the lower part of the barrel, and the powder above will lose much of its goodness.”
In the dawn of artillery, loose powder was brought to the gun in a covered bucket, usually made of leather. The loader scooped up the proper amount with a ladle (fig. 44), and inserted it into the gun. He could, by using his experienced judgment, put in just enough powder to give him the range he wanted, much as our modern artillerymen sometimes use only a portion of their charge. After Gustavus Adolphus in the 1630’s, however, powder bags came into wide use, although English gunners long preferred to ladle their powder. The powder bucket or “passing box” of course remained on the scene. It was usually large enough to hold a pair of cartridge bags.
The root of the word cartridge seems to be “carta,” meaning paper. But paper was only one of many materials such as canvas, linen, parchment, flannel, the “woolen stuff” of the 1860’s, and even wood. Until the advent of the silk cartridge, nothing was entirely satisfactory. The materials did not burn completely, and after several rounds it was mandatory to withdraw the unburnt bag ends with a wormer (fig. 44), else they accumulated to the point where they blocked the vent or “touch hole” by which the piece was fired. Parchment bags shriveled up and stuck in the vent, purpling many a good gunner’s face.