Figure 28—EIGHTEENTH CENTURY SPANISH GARRISON GUN
Figure 28—EIGHTEENTH CENTURY SPANISH GARRISON GUN.
Before the Castillo was completed, guns were mounted only in the bastions or projecting corners of the fort. A 1683 inventory clearly shows that heaviest guns were in the San Agustín, or southeastern bastion, commanding not only the harbor and its entrance but the town of St. Augustine as well San Pablo, the northwestern bastion, overlooked the land approach tothe Castillo and the town gate; and, though its armament was lighter, it was almost as numerous as that in San Agustín. Bastion San Pedro to the southwest was within the town limits, and its few light guns were a reserve for San Pablo. The watchtower bastion of San Carlos overlooked the northern marshland and the harbor; its armament was likewise small. The following list details the variety and location of the ordnance:
Cannon mounted at Castillo de San Marcos in 1683
Thetotal number of Castillo guns in service at this date was 27, but there were close to a dozen unmounted pieces on hand, including a pair of pedreros. The armament was gradually increased to 70-odd guns as construction work on the fort made additional space available, and as other factors warranted more ordnance. Below is a summary of Castillo armament through the years:
Armament of Castillo de San Marcos, 1683-1834
This tabulation reflects contemporary conditions quite clearly. The most serious invasions of Spanish Florida took place during the first half of the eighteenth century, precisely the time when the Castillo armament was strongest. While most of the guns were in battery condition, the table does have some pieces rated only fair and may also include a few unserviceables. Colonial isolation meant that ordnance often served longer than the normal 1,200-round life of an iron piece. A usual failure was the development ofcracks around the vent or in the bore. Sometimes a muzzle blew off. The worst casualties of the 1702 siege came from the bursting of an iron 16-pounder which killed four and seriously wounded six men. At that period, incidentally, culverins were the only guns with the range to reach the harbor bar some 3,000 yards away.
Although when the Spanish left Florida to Britain in 1763 they took serviceable cannon with them, two guns at Castillo de San Marcos National Monument today appear to be seventeenth century Spanish pieces. Most of the 24- and 32-pounder garrison cannon, however, are English-founded, after the Armstrong specifications of the 1730's, and were part of the British armament during the 1760's. Amidst the general confusion and shipping troubles that attended the British evacuation in 1784, some ordnance seems to have been left behind, to remain part of the defenses until the cession to the United States in 1821.
The Castillo also has some interesting United States guns, including a pair of early 24-pounder iron field howitzers (c. 1777-1812). During the 1840's the United States modernized Castillo defenses by constructing a water battery in the moat behind the sea wall. Many of the guns for that battery are extant, including 8-inch Columbiads, 32-pounder cannon, 8-inch seacoast and garrison howitzers. St. Augustine's Plaza even boasts a converted 32-pounder rifle.
Figure 29—VAUBAN'S MARINE CARRIAGE (c. 1700)
Figure 29—VAUBAN'S MARINE CARRIAGE (c. 1700).
Garrison and ship carriages were far different from field, siege, and howitzer mounts, while mortar beds were in a separate class entirely. Basic proportions for the carriage were obtained by measuring (1) the distance from trunnion to base ring of the gun, (2) the diameter of the base ring, and (3) the diameter of the second reinforce ring. The result was a quadrilateral figure that served as a key in laying out the carriage to fit the gun. Cheeks, or side pieces, of the carriage were a caliber in thickness, so the bigger the gun, the more massive the mount.
A 24-pounder cheek would be made of timber about 6 inches thick. The Spaniards often used mahogany. At Jamestown, in the early 1600's, Capt. John Smith reported the mounting of seven "great pieces of ordnance upon new carriages of cedar," and the French colonials also used this material. British specifications in the mid-eighteenth century called for cheeks and transoms of dry elm, which was very pliable and not likely to split; but some carriages were made of young oak, and oak was standard forUnited States garrison carriages until it was replaced by wrought-iron after the Civil War.
For a four-wheeled English carriage of 1750, height of the cheek was 4-2/3 diameters of the shot, unless some change in height had to be made to fit a gun port or embrasure. To prevent cannon from pushing shutters open when the ship rolled in a storm, lower tier carriages let the muzzle of the gun, when fully elevated, butt against the sill over the gun port.
On the eighteenth century Spanish garrison carriage (fig.28), no bolts were threaded; all were held either by a key run through a slot in the foot of the bolt, or by bradding the foot over a decorative washer. Compared with American mounts of the same type (figs.30and31), the Spanish carriage was considerably more complicated, due partly to the greater amount of decorative ironwork and partly to the design of the wooden parts which, with their carefully worked mortises, required a craftsman's skill. The cheek of the Spanish carriage was a single great plank. English and American construction called for a built-up cheek of several planks, cleverly jogged or mortised together to prevent starting under the strain of firing.
Figure 30—ENGLISH GARRISON CARRIAGE (1756).
Figure 30—ENGLISH GARRISON CARRIAGE (1756).By substituting wooden wheels for the cast-iron ones, this carriage became a standard naval gun carriage.
Müller furnished specifications for building truck (four-wheeled) carriages for 3- to 42-pounders. Aboard ship, of course, the truck carriage was standard for almost everything except the little swivel guns and the mortars.
Carriage trucks (wheels), unless they were made of cast iron, had iron thimbles or bushings driven into the hole of the hub, and to save the wood of the axletree, the spindle on which the wheel revolved was partly protected by metal. The British put copper on thebottomof the spindle; Spanish and French designers put copper on thetop, then set iron "axletree bars" into the bottom. These bars strengthened the axletree and resisted wear at the spindle.
A 24-pounder fore truck was 18 inches in diameter. Rear trucks were 16 inches. The difference in size compensated for the slope in the gun platform or deck—a slope which helped to check recoil. Aboard ship, where recoil space was limited, the "kick" of the gun was checked by a heavyrope called a breeching, shackled to the side of the vessel (see fig.11). Ship carriages of the two-or four-wheel type (fig.31), were used through the War between the States, and there was no great change until the advent of automatic recoil mechanisms made a stationary mount possible.
Figure 31—U. S. NAVAL TRUCK CARRIAGE (1866)
Figure 31—U. S. NAVAL TRUCK CARRIAGE (1866).
With garrison carriages, however, changes came much earlier. In 1743, Fort William on the Georgia coast had a pair of 18-pounders mounted upon "curious moving Platforms" which were probably similar to the traversing platforms standardized by Gribeauval in the latter part of the century. United States forts of the early 1800's used casemate and barbette carriages (fig.10) of the Gribeauval type, and the traversing platforms of these mounts made training (aiming the gun right or left) comparatively easy.
Training the old truck carriage had been heavy work for the handspikemen, who also helped to elevate or depress the gun. Maximum elevation or depression was about 15° each way—about the same as naval guns used during the Civil War. If one quoin was not enough to secure proper depression, a block or a second quoin was placed below the first. But before the gunner depressed a smoothbore below zero elevation, he had to put either a wad or a grommet over the ball to keep it from rolling out.
Ship and garrison cannon were not moved around on their carriages. If the gun had to be taken any distance, it was dismounted and chained under a sling wagon or on a "block carriage," the big wheels of which easily rolled over difficult terrain. It was not hard to dismount a gun: the keys locking the cap squares were removed, and then the gin was rigged and the gun hoisted clear of the carriage.
A typical garrison or ship cannon could fire any kind of projectile, but solid shot, hot shot, bombs, grape, and canister were in widest use. These guns were flat trajectory weapons, with a point-blank range of about 300 yards. They were effective—that is, fairly accurate—up to about half a mile, although the maximum range of guns like the Columbiad of the nineteenth century, when elevation was not restricted by gun port confines, approached the 4-mile range claimed by the Spanish for the sixteenth centuryculverin. The following ranges of United States ordnance in the 1800's are not far different from comparable guns of earlier date.
Ranges of United States smoothbore garrison guns of 1861
Ranges of United States naval smoothbores of 1866
Ranges of United States naval rifles in 1866
In accuracy and range the rifle of the 1860's far surpassed the smoothbores, but such tremendous advances were made in the next few decades with the introduction of new propellants and steel guns that the performances of the old rifles no longer seem remarkable. In the eighteenth century, a 24-pounder smoothbore could develop a muzzle velocity of about 1,700 feet per second. The 12-inch rifled cannon of the late 1800's had a muzzle velocity of 2,300 foot-seconds. In 1900, the Secretary of the Navy proudly reported that the new 12-inch guns forMaine-class battleships produced a muzzle velocity of 2,854 foot-seconds, using an 850-pound projectile and a charge of 360 pounds of smokeless powder. Such statistics elicit a chuckle from today's artilleryman.
Field counterpart of the garrison cannon was the siege gun—the "battering cannon" of the old days, mounted upon a two-wheeled siege or "traveling"carriage that could be moved about in field terrain. Whereas the purpose of the garrison cannon was to destroy the attacker and his matériel, the siege cannon was intended to destroy the fort. Calibers ranged from 3- to 42-pounders in eighteenth century English tables, but the 18- and 24-pounders seem to have been the most widely used for siege operations.
Figure 32—SPANISH EIGHTEENTH CENTURY SIEGE CARRIAGE
Figure 32—SPANISH EIGHTEENTH CENTURY SIEGE CARRIAGE.
The siege carriage closely resembled the field gun carriage, but was much more massive, as may be seen from these comparative figures drawn from eighteenth century English specifications:
Heavy siege guns were elevated with quoins, and elevation was restricted to 12° or less, which was about the same as United States siege carriages permitted in 1861. It was considered ample for these flat trajectory pieces.
Both field and siege carriages were pulled over long distances by lifting the trail to a horse-or ox-drawn limber; a hole in the trail transom seated on an iron bolt or pintle on the two-wheeled limber. Some late eighteenth century field and siege carriages had a second pair of trunnion holes a couple of feet back from the regular holes, and the cannon was shifted to the rear holes where the weight was better distributed for traveling. The United States siege carriage of the 1860's had no extra trunnion holes, but a "traveling bed" was provided where the gun was cradled in position 2 or 3 feet back of its firing position. A well-drilled gun crew could make the shift very rapidly, using a lifting jack, a few rollers, blocks, and chocks. When there was danger of straining or breaking the gun carriage, however, massive block carriages, sling carts, or wagons were used to carry the guns.
Slingwagons were of necessity used for transport in siege operations when the guns were to be mounted on barbette (traversing platform) carriages (fig.10). Emplacing the barbette carriage called for construction of a massive, level subplatform, but it also eliminated the old need for the gunner to chalk the location of his wheels in order to return his gun to the proper firing position after each shot.
The Federal sieges of Forts Pulaski and Sumter were highly complicated engineering operations that involved landing tremendously heavy ordnance (the 300-pounder Parrott weighed 13 tons) through the surf, moving the big guns over very difficult terrain and, in some cases, building roads over the marshes and driving foundation piles for the gun emplacements.
The heavy caliber Parrotts trained on Fort Sumter were in batteries from 1,750 to 4,290 yards distant from their target. They were very accurate, but their endurance was an uncertain factor. The notorious "Swamp Angel," for instance, burst after 36 rounds.
Figure 33—SPANISH 4-POUNDER FIELD CARRIAGE (c. 1788).
Figure 33—SPANISH 4-POUNDER FIELD CARRIAGE (c. 1788).This carriage, designed on the "new method," employed a handscrew instead of a wedge for elevating the piece, a—The handspike was inserted through eyebolts in the trail, b—The ammunition locker held the cartridges.
The field guns were the mobile pieces that could travel with the army and be brought quickly into firing position. They were lighter in weight thanany other type of flat trajectory weapon. To achieve this lightness the designers had not only shortened the guns, but thinned down the bore walls. In the eighteenth century, calibers ran from the 3- to the 24-pounder, mounted on comparatively light, two-wheeled carriages. In addition, there was the 1-1/2-pounder (and sometimes the light 3- or 6-pounder) on a "galloper" carriage—a vehicle with its trail shaped into shafts for the horse. The elevating-screw mechanism was early developed for field guns, although the heavier pieces like the 18- and 24-pounders were still elevated by quoins as late as the early 1800's.
In the Castillo collection are parts of early United States field carriages little different from Spanish carriages that held a score of 4-pounders in the long, continuous earthwork parapet surrounding St. Augustine in the eighteenth century. The Spanish mounts were a little more complicated in construction than English or American carriages, but not much. Spanish pyramid-headed nails for securing ironwork were not far different from the diamond-and rose-headed nails of the English artificer.
Each piece of hardware on the carriage had its purpose. Gunner's tools were laid in hooks on the cheeks. There were bolts and rings for the lines when the gun had to be moved by manpower in the field. On the trail transom, pintle plates rimmed the hole that went over the pintle on the limber. Iron reinforced the carriage at weak points or where the wood was subject to wear. Iron axletrees were common by the late 1700's.
For training the field gun, the crew used a special handspike quite different from the garrison handspike. It was a long, round staff, with an iron handle bolted to its head (fig.33a). The trail transom of the carriage held two eyebolts, into which the foot of the spike was inserted. A lug fitted into an offset in the larger eyebolt so that the spike could not twist. With the handspike socketed in the eyebolts, lifting the trail and laying the gun was easy.
The single-trail carriage (fig.13) used so much during the middle 1800's was a remarkable simplification of carriage design. It was also essential for guns like the Parrott rifles, since the thick reinforce on the breech of an otherwise slender barrel would not fit the older twin-trail carriage. The single, solid "stock" or trail eliminated transoms, for to the sides of the stock itself were bolted short, high cheeks, humped like a camel to cradle the gun so high that great latitude in elevation was possible. The elevating screw was threaded through a nut in the stock, right under the big reinforce of the gun.
While the larger bore siege Parrotts were not noted for long serviceability, Parrott field rifles had very high endurance. As for performance, see the following table:
Ranges of Parrott field rifles (1863)
Amazingly enough, these ranges were obtained with about the same amount of powder used for the smoothbores of similar caliber: the 10-pounder Parrott used only a pound of powder; the 20-pounder used a two-pound charge; and the 30-pounder, 3-1/4 pounds!
The howitzer was invented by the Dutch in the seventeenth century to throw larger projectiles (usually bombs) than could the field pieces, in a high trajectory similar to the mortar, but from a lighter and more mobile weapon. The wide-purpose efficiency of the howitzer was appreciated almost at once, and it was soon adopted by all European armies. The weapon owed its mobility to a rugged, two-wheeled carriage like a field carriage, but with a relatively short trail that permitted the wide arc of elevation needed for this weapon.
Figure 34—SPANISH 6-INCH HOWITZER (1759-88).
Figure 34—SPANISH 6-INCH HOWITZER (1759-88).This bronze piece was founded during the reign of Charles III and bears his shield. a—Dolphin, or handle, b—Bore, c—Powder chamber.
English howitzers of the 1750's were of three calibers: 5.8-, 8-, and 10-inch, but the 10-incher was so heavy (some 50 inches long and over 3,500 pounds)that it was quickly discarded. Müller deplored the superfluous weight of these pieces and developed 6-, 8-, 10, and 13-inch howitzers in which, by a more calculated distribution of the metal, he achieved much lighter weapons. Müller's howitzers survived in the early 6- to 10-inch pieces of United States artillery and one fine little 24-pounder of the late eighteenth century happens to be among the armament of Castillo de San Marcos, along with some early nineteenth century howitzers. The British, incidentally, were the first to bring this type gun to Florida. None appeared on the Castillo inventory until the 1760's.
Figure 35—ENGLISH 8-INCH "HOWITZ" CARRIAGE (1756).
Figure 35—ENGLISH 8-INCH "HOWITZ" CARRIAGE (1756).The short trail enabled greater latitude in elevating the howitzer.
In addition to the very light and therefore easily portable mountain howitzer used for Indian warfare, United States artillery of 1850 included 12-, 24-, and 32-pounder field, 24-pounder and 8-inch siege and garrison, and the 10-inch seacoast howitzer. The Navy had a 12-pounder heavy and a 24-pounder, to which were added the 12- and 24-pounder Dahlgren rifled howitzers of the Civil War period. Such guns were often used in landing operations. The following table gives some typical ranges:
Ranges of U. S. Howitzers in the 1860's