NPS Interpretive Series: Artillery Through the Ages (2024)

THE CHARACTERISTICS OF CANNON

THE EARLY SMOOTHBORE CANNON

Soon after he found he could hurl a rock with hisgood right arm, man learned about trajectory—the curved path takenby a missile through the air. A baseball describes a "flat" trajectoryevery time the pitcher throws a hard, fast one. Youngsters tossing theball to each other over a tall fence use "curved" or "high" trajectory.In artillery, where trajectory is equally important, there are threemain types of cannon: (1) the flat trajectory gun, throwing shot at thetarget in relatively level flight; (2) the high trajectory mortar, whoseshell will clear high obstacles and descend upon the target from above;and (3) the howitzer, an in-between piece of medium-high trajectory,combining the mobility of the fieldpiece with the large caliber of themortar.

The Spaniard, Luis Collado, mathematician, historian,native of Lebrija in Andalusia, and, in 1592, royal engineer of HisCatholic Majesty's Army in Lombardy and Piedmont, defined artillerybroadly as "a machine of infinite importance." Ordnance he divided intothree classes, admittedly following the rules of the "German masters,who were admired above any other nation for their founding and handlingof artillery." Culverins and sakers (Fig. 23a) were guns of the firstclass, designed to strike the enemy from long range. The batteringcannon (fig. 23b) were second class pieces; they were to destroy fortsand walls and dismount the enemy's machines. Third class guns firedstone balls to break and sink ships and defend batteries from assault;such guns included the pedrero, mortar, and bombard (fig. 23c,d).

Collado's explanation of how the various guns wereinvented is perhaps naive, but nevertheless interesting: "Although themain intent of the inventors of this machine [artillery] was to fire andoffend the enemy from both near and afar, since this offense must be indiverse ways it so happened that they formed various classes in thismanner: they came to realize that men were not satisfied with theespingardas [small Moorish cannon], and for this reason themusket was made; and likewise the esmeril and the falconet. Andalthough these fired longer shots, they made the demisaker. To remedy adefect of that, thesakers were made, and the demiculverins and culverins. While they weredeemed sufficient for making a long shot and striking the enemy fromafar, they were of little use as battering guns because they fire asmall ball. So they determined to found a second kind of piece,wherewith, firing balls of much greater weight, they might realize theirintention. But discovering like-wise that this second kind of piece wastoo powerful, heavy and costly for batteries and for defense againstassaults or ships and galleys, they made a third class of piece, lighterin metal and taking less powder, to fire balls of stone. These are thecommonly called cañones de pedreros. All the classes of piecesare different in range, manufacture and design. Even the method ofcharging them is different."

FIGURE 22—TRAJECTORIES. Maximum range of eighteenth century gunswas about 1 mile.
Guns could: Batter heavy construction with solid shot at long orshort range; destroy fort parapets and, by ricochet fire, dismountcannon; shoot grape, canister, or bombs against massed personnel.
Mortars could: Reachtargets behind obstructions; use high angle fire to shoot bombs,destroying construction and personnel.
Howitzers could:Move more easily in the fieldthan mortars; reach targets behind obstructions by high angle fire;shoot larger projectiles than could field guns of similar weight.

It was most important for the artillerist tounderstand the different classes of guns. As Collado quaintly phrasedit, "he who ignores the present lecture on this arte will, Iassert, never do a good thing." Cannon burst in the batteries every daybecause gunners were ignorant of how the gun was made and what it wasmeant to do. Nor was such ignorance confined to gunners alone. The willand whim of the prince who ordered the ordnance or "the simple opinionof the unexpert founder himself," were the guiding principles in gunfounding. "I am forced," wrote Collado, "to persuade the princes andadvise the founders that the making of artillery should always take intoaccount the purpose each piece must serve." This persuasion he undertookin considerable detail.

The first class of guns were the long-range pieces,comparatively "rich" in metal. In the following table from Collado, thecalibers and ranges for most Spanish guns of this class are given,although as the second column shows, at this period calibers werestandardized only in a general way. For translation where possible, andto list those which became the most popular calibers, we have added afinal column. Most of the guns were probably of culverin length: 30- to32-caliber.

FIGURE 23—SIXTEENTH CENTURY SPANISH ARTILLERY. Taken froma 1592 manuscript, these drawings illustrate the three mainclasses of artillery used by Spain during the early colonial period inthe New World. a—Culverin (Class1). b—Cannon (Class 2). c—Pedrero (Class 3). d—Mortar(Class 3).

In view of the range Collado ascribes to the culverin, some remarks ongun performances are in order. "Greatest random" was what the old timegunner called his maximum range, and random it was. Beyond point-blankrange, the gunner was never sure of hitting his target. So withsmoothbores, long range was never of great importance. Culverins, withtheir thick walls, long bores, and heavy powder charges, achieveddistance; but second class guns like field "cannon," with less metal andsmaller charges, ranged about 1,600 yards at a maximum, while theeffective range was hardly more than 500. Heavier pieces, such as the French33-pounder battering cannon, might have a point-blank range of 720yards; at 200-yard range its ball would penetrate from 12 to 24 feet ofearthwork, depending on how "poor and hungry" the earth was. At 130yards a Dutch 48-pounder cannon put a ball 20 feet into a strong earthrampart, while from 100 yards a 24-pounder siege cannon would bury theball 12 feet.

But generalizations on early cannon aredifficult, for it is not easy to find two "mathematicians" of the olddays whose ordnance lists agree. Spanish guns of the late 1500's do,however, appear to be larger in caliber than pieces of similar name inother countries, as is shown by comparing the culverins: the smallestSpanish culebrina was a 20-pounder, but the French greatcouleurine of 1551 was a 15-pounder and the typical Englishculverin of that century was an 18-pounder.Furthermore, midway of the 1500's, Henry II greatly simplified Frenchordnance by holding his artillery down to the 33-pounder cannon,15-pounder great culverin, 7-1/2-pounder bastard culverin, 2-poundersmall culverin, a 1-pounder falcon, and a 1/2-pounder falconet.Therefore, any list like the one following must have its faults:

Like many gun names, the word "culverin" has ametaphorical meaning. It derives from the Latin colubra (snake).Similarly, the light gun called áspide or aspic, meaning"asp-like," was named after the venomous asp. But these digressionsshould not obscure the fact that both culverins and demiculverins werehighly esteemed on account of their range and the effectiveness of fire.They were used for precision shooting such as building demolition, andan expert gunner could cut out a section of stone wall with these gunsin short order.

As the fierce falcon hawk gave its name to the falconand falconet, so the saker was named for the saker hawk; rabinet,meaning "rooster," was therefore a suitable name for the falcon'ssmall-bore cousin. The 9-pounder saker served well in any militaryenterprise, and the moyana (or the French moyenne,"middle-sized"), being a shorter gun of saker caliber, was a good navalpiece. The most powerful of the smaller pieces, however, was thepasavolante, distinguishable by its great length. It was between40 and 44 calibers long! In addition, it had thicker-bore walls than anyother small caliber gun, and the combination of length and weightpermitted an unusually heavy charge—as much powder as the ballweighed. A 6-pound lead ball was what the typical pasavolantefired; another gun of the same caliber firing an iron ball would be a4-pounder. The point-blank range of this Spanish gum was a football field's lengthfarther than either the falcon or demisaker.

In today's Spanish, pasavolante means "fastaction," a phrase suggestive of the vicious impetuosity to be expectedfrom such a small but powerful cannon. Sometimes it was termed adrajon, the English equivalent of which may be the drake, meaning"dragon"; but perhaps its most popular name in the early days wascerbatana, from Cerebus, the fierce three-headed dog ofmythology. Strange things happen to words: a cerbatana in modernSpanish is a pea shooter.

The second class of guns were the only ones properlycalled "cannon's in this early period. They were siege and batteringpieces, and in some few respects were similar to the howitzers of lateryears. A typical Spanish cannon was only about two-thirds as long as aculverin, and the bore walls were thinner. Naturally, the powder chargewas also reduced (half the ball's weight for a common cannon, while aculverin took double that amount).

The Germans made their light cannon 18 calibers long.Most Spanish siege and battering guns had this same proportion, for ashorter gun would not burn all the powder efficiently, "which," saidCollado, "is a most grievous fault." However, small cannon of 18-caliberlength were too short; the muzzle blast tended to destroy the embrasureof the parapet. For this reason, Spanish demicannon were as long as 24calibers and the quarter-cannon ran up to 28. The 12-pounderquarter-cannon, incidentally, was "culverined" or reinforced so that itactually served in the field as a demiculverin.

The great weight of its projectile gave the doublecannon its name. The warden of the Castillo at Milan had some130-pounders made, but such huge pieces were of little use, except inpermanent fortifications. It took a huge crew to move them, theircarriages broke under the concentrated weight, and they consumedmountains of munitions. The lombard, which apparently originated inLombardy, and the basilisk had the same disadvantages. The fabledbasilisk was a serpent whose very look was fatal.Its namesake in bronze was tremendously heavy, withwalls up to 4 calibers thick and a bore up to 30 calibers long. It wasseldom used by the Europeans, but the Turkish General Mustafa had a pairof basilisks at the siege of Malta, in 1565, that fired 150- and200-pound balls. The 200-pounder gun broke loose as it was beingtransferred to a homeward bound galley and sank permanently to thebottom of the sea. Its mate was left on the island, where it became anobject of great curiosity.

The third class of ordnance included the guns firingstone projectiles, such as the pedrero (or perrier, petrary, cannonpetro, etc.), the mortars, and the old bombards like Edinburgh Castle'sfamous Mons Meg. Bars of wrought iron were welded together to form Meg'stube, and iron rings were clamped around the outside of the piece. Inspite of many accidents, this coopering technique persisted through thefifteenth century. Mons Meg was made in two sections that screwedtogether, forming a piece 13 feet long and 5 tons in weight.

Pedreros (fig. 23c) were comparatively light. Thefoundryman used only half the metal he would put into a culverin, forthe stone projectile weighed only a third as much as an iron ball of thesame size, and the bore walls could therefore be comparatively thin.They were made in calibers up to 50-pounders. There was a chamber forthe powder charge and little danger of the gun's bursting, unless afoolhardy fellow loaded it with an iron ball. The wall thicknesses ofthis gun are shown in Figure 24, where the inner circle represents thediameter of the chamber, the next arc the bore caliber, and the outerlines the respective diameters at chase, trunnions, and vent.

FIGURE 24—HOW MUCH METAL WAS IN EARLY GUNS? Thecharts compare the wall diameters of sixteenth-seventeenth centurytypes. The center circle represents the bore, while the three outer arcsshow the relative thickness of the bore wall at (1) the smallestdiameter of the chase, (2) at the trunnions, and (3) at the vent. Thesmall arc inside the bore indicates the powder chamber found in thepedrero and mortar.

Mortars (fig. 23d) were excellent for "putting greatfear and terror in the souls of the besieged." Every night the mortarswould play upon the town: "it keeps them in constant turmoil, due to thethought that some ball will fall upon their house." Mortars weredesigned like pedreros, except much shorter. The convenient way tocharge them was with saquillos (small bags) of powder. "Theyrequire," said Collado, "a larger mouthful than any other pieces."

Just as children range from slight to stocky in thesame family, there are light, medium, or heavy guns—all bearing thesame family name. The difference lies in how the piece was "fortified";that is, how thick the founder cast the bore walls. The English languagehas inelegantly descriptive terms for the three degrees of"fortification": (1) bastard, (2) legitimate, and (3)double-fortified. The thicker-walled guns used more powder. Spanishdouble-fortified culverins were charged with the full weight of the ballin powder; four-fifths that amount went into the legitimate, and onlytwo-thirds for the bastard culverin. In a short culverin (say, 24calibers long instead of 30), the gunner used 24/30 of a standardcharge.

The yardstick for fortifying a gun was its caliber.In a legitimate culverin of 6-inch caliber, for instance, the borewall at the vent might be one caliber (16/16 of the bore diameter) or 6inches thick; at the trunnions it would be 10/16 or 4-1/8 inches, andat the smallest diameter of the chase, 7/16 or 2-5/8 inches. This tablecompares the three degrees of fortification used in Spanishculverins:

As with culverins, so with cannon. This is Collado'stable showing the fortification for Spanish cannon:

Since cast iron was weaker than bronze, the walls of cast-iron pieceswere even thicker than the culverins. Spanish iron guns were foundedwith 300 pounds of metal for each pound of the ball, and in lengths from18 to 20 calibers. English, Irish, and Swedish iron guns of the period,Collado noted, had slightly more metal in them than even the Spaniardsrecommended.

FIGURE 25—SIXTEENTH CENTURY CHAMBERED CANNON. a—"Bell-chambered"demicannon. b—Chambered demicannon.

Another way the designers tried to gain strengthwithout loading the gun with metal was by using a powder chamber. Achambered cannon (fig. 25b) might be fortified like either the light orthe common cannon, but it would have a cylindrical chamber abouttwo-thirds of a caliber in diameter and four calibers long. It was notalways easy, however, to get the powder into the chamber. Colladoreported that many a good artillerist dumped the powder almost in themiddle of the gun. When his ladle hit the mouth of the chamber, hethought he was at the bottom of the bore! The cylindrical chamber wassomewhat improved by a cone-shaped taper, which the Spaniards calledencampanado or "bell-chambered." A cañon encampanado(fig. 25a) was a good long-range gun, strong, yet light. But it was hardto cut a ladle for the long, tapered chamber.

Of all these guns, the reinforced cannon, was one ofthe best. Since it had almost as much metal as a culverin, it lacked thedefects of the chambered pieces. A 60-pounder reinforced cannon fireda convenient 55-pound ball, was easy to move, load, and clean, and heldup well under any kind of service. It cooled quickly. Either cannonpowder or fine powder (up to two-thirds the ball's weight) could be usedin it. Reinforced cannon were an important factor in any enterprise, asKing Philip's famed "Twelve Apostles" proved during the Flanderswars.

While there was little real progress in mobilityuntil the days of Gustavus Adolphus, the wheeled artillery carriageseems to have been invented by the Venetians in the fifteenth century.The essential parts of the design were early established: two large,heavy cheeks or side pieces set on an axle and connected by transoms.The gun was cradled between the cheeks, the rear ends of which formed a"trail" for stabilizing and maneuvering the piece.

Wheels were perhaps the greatest problem. As early asthe 1500's carpenters and wheelwrights were debating whether dishedwheels were best. "They say," reported Collado, "that the[dished] wheel will never twist when the artillery is on the march.Others say that a wheel with spokes angled beyond the cask cannot carrythe weight of the piece without twisting the spoke, so the wheel doesnot last long. I am of the same opinion, for it is certain that aperpendicular wheel will suffer more weight than the other. The defectof twisting under the pieces when on the march will be remedied bymaking the cart a little wider than usual." However, advocates of thedished wheel finally won.