Introduction to Artillery

Artillery, weapons, including cannon and missile launchers, that fire projectiles larger than approximately one-half inch (13 mm) in diameter. In the United States, any gun or launcher which makes use of ammunition 1 inch (2.5 centimeters) or more in diameter and that is not fired from the hand or shoulder is called artillery. These weapons normally fire high-explosive projectiles that can reach targets far beyond the range of small arms such as pistols, rifles, and machine guns. An artillery battery consists of two or more pieces (the general term used for individual weapons) of the same size and type that are usually controlled and fired together.

Artillery is also the name of the branch of an army that mans such weapons. Artillery is one of the three main combat arms, the others being infantry and armor (tanks). The distinction between these three arms is not primarily one of weapons—since tanks are armed with artillery-size guns and even infantrymen fire such artillery pieces as mortars and recoilless rifles—but of how the weapons are used.

In the artillery, the weapons are placed some distance behind the fighting front and the projectiles pass over the heads of friendly troops. The guns are used to inflict casualties and destroy or damage enemy defensive positions before an infantry or tank attack; to break up an enemy attack before the attackers come within range of infantry weapons; to harass and demoralize enemy troops; and to destroy enemy artillery, tanks, trucks, aircraft, or ships.

Artillery fire is generally more accurate than aerial bombing, and can be kept up day and night in any weather. Accuracy comes from the use of various fire-control instruments—including telescopes, range finders, lasers, and radar—and mathematical calculations based on data obtained with these instruments and the known characteristics of the guns and ammunition being fired. Forward observers, either on the ground or in the air, play an important role in directing artillery fire.

Armor plate, such as that used on tanks and naval vessels, provides some defense against artillery fire. Concrete bunkers and blockhouses are effective, but they limit the mobility of the defending troops. The main defense of the infantryman is usually a foxhole or underground bunker. Helmets and body armor provide some protection against stray shell fragments and flying debris. Active defensive measures include artillery or air attacks on the enemy guns.

Parts of An Artillery Weapon

The typical artillery weapon has two main parts—the barrel and the carriage. The barrel consists of two openings – ‘muzzle’ and ‘breech’. The opening where the shell comes out is called muzzle. A weapon contains either a rifled or a smooth bore. The bore (inside) of the barrel generally contains spiral grooves, called rifling, that cause the projectile to spin in flight, increasing its accuracy. The bore of the gun that contains ammunition with fins, which steady shells in flight, is called smooth-bore. The firing mechanism has a primer, used for guns with larger caliber or a firing pin for smaller weapons. A primer ignites the propellant in the ammunition. This propellant builds up a high pressure and then the projectile is forced to move out of the muzzle at high velocity, that is speed. The rear of the barrel is called the breech, where the ammunition is inserted. Most artillery weapons are loaded from the breech, either automatically through a slot or manually through a door called the breech-block. The breechblock closes the breech tightly. Generally, the breech-block contains the firing pin or firing mechanism.

The carriage consists of a recoil mechanism—a spring or hydraulic device that absorbs part of the backward-pushing force caused by the firing—and a mounting device that permits the gun or barrel to be traversed (pivoted) and the barrel to be pointed upward at varying angles. The carriage is generally mounted on wheels or on a tracked vehicle with a chassis similar to that of a tank. Some guns are protected by armor plate.

Small guns that fire at targets visible to the gunners are aimed by optical sights attached to the weapon itself. Larger guns are aimed, sometimes automatically, by separate sighting and computing devices. In one system, a forward observer uses a laser aiming device to determine the target's position and the data thus obtained is relayed electronically to a computer; the computer transmits aiming and firing data to the appropriate gun position.

Artillery Types

Artillery is generally divided according to size into light artillery, medium artillery, and heavy artillery. It can also be categorized by the trajectory, it imparts to the projectile. The size of an artillery weapon is usually expressed in terms of its caliber (the diameter of its bore) measured in millimeters or inches and fractions of inches. (In large guns, especially naval guns, the term caliber is also used as a measure of length. For example, a 6-inch 25-caliber gun is one with a bore diameter of 6 inches [152 mm] and an inside length 25 times the bore diameter.) The size of guns is occasionally expressed by the weight of the ammunition fired; thus a "six pounder" fires a projectile weighing six pounds (2.7 kg).

Army Artillery

Traditionally, artillery weapons were called cannon and three kinds were recognized—guns, howitzers, and mortars. They are defined by the kind of trajectory (path) followed by their projectiles. Guns and howitzers not mounted on tanks, ships, or aircraft are often called field pieces, or field artillery.

Field artillery is utilized to support infantry and armored forces. Generally, these weapons are dragged behind tractors or trucks or boarded on vehicles for their speedy execution. The size of the weapons ranges from guns firing 1-pound (0.5-kilogram) projectiles to those firing 350-pound (159-kilogram) projectiles. The caissons which were once used to carry ammunition for field artillery are now being replaced by ammunition trailers and tractors. The size of weapons is measured in millimeters, ranging from 75 to 125 millimeters. These weapons are put on tanks and tank destroyers. Field artillery is supplemented by surface-to-surface guided missiles.

Antiaircraft artillery refers to the bursting shells fired rapidly from antiaircraft artillery at a high angle. Generally, these guns are aimed at a target by electronic automatic fire control systems. The shells are exploded with the help of special fuses especially in the area of target. Antiaircraft guns are supplemented by surface-to-surface guided missiles.

Artillery also sometimes refers to the cannons on airplanes, helicopters and naval vessels.

A Gun

is a weapon that has a low, or nearly flat, trajectory—it fires projectiles in a nearly straight or gently curving line. A gun's barrel is long in relation to its diameter. Guns are used against airplanes and tanks and as long-range bombardment weapons. The main weapon of a tank is usually a gun. Guns used by the U.S. Army include the 20-mm automatic cannon (a type of rapid-fire gun); the 75-mm and 90-mm antiaircraft guns; and the 90-mm, 105-mm, and 120-mm tank guns. The United States armed forces no longer use guns as field pieces.

A Howitzer,

usually used as a field piece, has a higher trajectory than a gun—its projectiles follow a more pronounced curve. Guns have greater range than howitzers firing similar ammunition, but are less adaptable to firing over the heads of friendly troops or to reaching targets protected by hills.

The U.S. Army uses a variety of howitzers: the 105-mm towed field piece; the 155-mm field pieces, towed and self-propelled; and the 203-mm self-propelled field piece.

A Mortar

has a very high trajectory; its shells are fired high into the air and plunge almost straight down. Most mortars, unlike guns and howitzers, are loaded from the muzzle (front end of the barrel) rather than from the breech. Since they have short, smoothbore barrels (that is, barrels without rifling), they are short-range weapons of limited accuracy.

Until World War I, mortars were large weapons manned by artillerymen. In that war the trench mortar was developed, and it became an infantry weapon. This mortar, the type now used, consists of a tube resting on a heavy metal base. The shell is dropped down the muzzle. When it hits the bottom of the tube, an explosive charge that fires the shell is set off. The United States armed forces use 60-mm and 81-mm light mortars and a 120-mm heavy mortar.

These three traditional types of artillery weapons are still in use, but other kinds are now used as well. These include missiles, rockets, and recoilless rifles.

Missiles and Rockets

are of many types—from the infantryman's bazooka to nuclear-armed intercontinental ballistic missiles designed to destroy entire cities. Between these extremes are a variety of surface-to-surface missiles, such as the U.S. Army's Lance, which are used as conventional artillery. Missiles, like artillery guns, are also used as antitank weapons. Some are guided by wire and some by computer-controlled infrared devices. There are also many surface-to-air missiles used as antiaircraft weapons.

Recoilless Rifles

are lightweight guns of 50 to 120 mm that can be fired by infantrymen, who carry the rifles either by hand or by vehicles. These rifles fire shells that are the size of small caliber artillery shells. They have little or no recoil, and therefore do not need heavy carriages. The breech of a recoilless rifle is not closed tightly, as is that of a conventional weapon, but is designed to permit some of the powder gases to escape to the rear and thus offset the normal recoil.

Naval Artillery

Although the term artillery is generally limited to land-based weapons, naval guns are of similar design and are used in similar ways. Modern naval cannon are almost always guns, rather than howitzers or mortars. Gunnery at sea is more complicated than on land because the ship doing the firing is always in motion.

Naval guns and missiles are designed for bombardment of ships and shore targets, and for use against aircraft. Naval guns and missiles are used against shore targets for a variety of purposes—to destroy strategic installations such as piers or airfields; to neutralize fortifications prior to an invasion or raid; and to support friendly troops already ashore.

The largest guns normally in service are the 8-inch (203-mm) and 6-inch (152-mm) guns mounted by certain cruisers. Battleships, which have occasionally seen service since World War II, have 16-inch (406-mm) guns. Large guns are housed, usually in groups of three, in a turret, a heavily armored, boxlike enclosure. The turret rotates together with all of its below-deck loading and operating machinery.

Smaller guns, those of 5 inches (127 mm) and less, are housed in rotating mounts which are sometimes enclosed in light armor. Mounts contain from one to four guns. Some of these guns, such as the U.S. Navy's 5-inch 54-caliber gun, can be used against both air and surface targets. Most antiaircraft guns load automatically and are fired remotely by a computer.

Missiles have replaced guns for many purposes on naval vessels; some ships, such as the Polaris submarines, are armed only with missiles. (

Mostly all cannon were cast in brass, bronze, or cast iron until post-American Civil War, 1861-1865. Manufacturers would also add more metal to make the barrel walls thicker in order to make the cannon stronger.

In the late 19th century, manufacturers made larger guns by forging, where workers melt the steel in a furnace, then pour it into a gun or ingot mold so that it cools. Then the metal is reheated to about 2100 degrees F (1150 degrees C) and hydraulic hammers or presses are utilized to forge it into shape.

In today’s times, most gun tubes are made by the mono-block method due to the development of high-strength steels. Here the manufacturers increase the strength of the tube by expanding it under internal pressure until the interior diameter of the tube has been permanently enlarged. When the pressure is released, the outer layers of metal tend to shrink to their original dimensions, but the inner layers tend to maintain their enlarged diameter. This results in a compression of the inner layers. Cold working or autofrettage is another name given to this process. The tube is annealed or tempered after it has been formed by being heated and slowly cooled. The next step is for the workers to machine it to its final specifications.

The gun is rifled after final machining. Workers cut grooves in the finished bore surface of the gun. The grooves are not cut directly into the barrel, but sometimes are cut into a separate tube called a liner, which can be inserted into the barrel. A rifled liner can be replaced with a new liner when it becomes worn, but due to the high cost of construction, their use has been limited.

History

Early Artillery

The first firearms appeared in Europe in the 14th century. At this time, artillery was first used in wars. Three cannon were used at the Battle of Cré cy in 1346, but they were not very effective. Small cannon were used by the French in 1450 against English and artillery was used in the final campaign in 1453 by Ottomans under Mehmet II to capture Constantinople. Bombards, tubes of brass or copper mounted on wooden sledges, fired stones or darts. Late in the century wrought-iron bombards appeared, firing iron balls. Some huge guns were made in the 15th century. A wrought-iron bombard called "Mons Meg," preserved in Scotland, has a bore of 20 inches (508 mm); it fired a 300-pound (136-kg) stone ball. The first mortars date from this period. By the mid-15th century the French were using long guns called culverins, mounted on wheels.

King Gustavus Adolphus of Sweden in the 17th century aided in the development of a short cast-iron gun that could accompany his troops. He increased rate of fire by having measured charges prepared in advance—the first cartridges. In the 18th century, Frederick the Great made important tactical use of artillery. He massed heavy fortress guns to support his attacks, and at the head of each infantry battalion placed a light six-pounder gun.

When Jean Gribeauval became France's inspector general in 1776, he found a wide variety of guns in use. He standardized horse-drawn gun carriages and introduced aiming devices. His reorganization of artillery was of great benefit to Napoleon I. Huge concentrations of artillery fire aided in winning Napoleon's later victories. Napoleon was the first one who collected his artillery in a grande batterie or big battery and directed his artillery fire on one point in the enemy's line, and then sent troops against that point. Instead of scattering guns among infantry battalions, Napoleon grouped them under division command.

The Americans during the Revolutionary War had little artillery, but they made effective use of guns captured at Ticonderoga and Saratoga. After the war a company of artillery at West Point with a detachment at Fort Pitt (Pittsburgh), was the only army unit retained in service.

In the War of 1812 British forces used rockets developed by William Congreve. These were mentioned by Francis Scott Key in "The Star-Spangled Banner" when he referred to "the rockets' red glare." Rockets were rarely used again until World War II.

Most of the guns in use at the beginning of the American Civil War were muzzle-loading, smoothbore iron cannon little different from those used by Gustavus Adolphus. The gun carriage, called a limber, had an ammunition chest and was usually drawn by six horses hitched in pairs. Accompanying the gun was a caisson, a wheeled vehicle carrying two ammunition chests, also drawn by six horses. Except for the drivers, the gun crew walked alongside. Batteries, usually of light guns, in which all men were mounted on horses were called horse artillery and normally served with cavalry.

Development of Modern Artillery

Effective breech-loading rifled guns were used by the French in their war against Austria in 1859, but smoothbores continued in use through the Franco-Prussian War of 1870–71. In that war the Prussians massed steel breech-loading guns in the main battle line, a practice that was widely used in World War I. Also during the 19th century there was much development of high explosives.

In 1907 the U.S. Army established the Coast Artillery and Field Artillery as separate arms; the Coast Artillery manned fixed guns in coastal fortifications while the Field Artillery was assigned smaller weapons for use in support of troops.

Artillery was employed on a huge scale in World War I. Shells containing poison gas, as well as high-explosive shells, were used. By the use of range finders, telescopic sights, and other fire-control instruments, artillery could be fired accurately from concealed positions and over the heads of friendly troops. As accuracy improved, guns of various sizes and ranges could concentrate fire on a narrow strip of enemy-held territory in preparation for an attack. This kind of artillery firing was called a barrage. If the curtain of fire was kept moving ahead of advancing troops, it was called a rolling barrage.

In the World War I (1914-1918), the troops who fought on the Western front dug out immense mazes of trenches. The warring sides generally exchanged fire between big-gun batteries. In the trench warfare of World War I, 14-inch (356-mm) naval guns and railway and fixed-mount guns of the Coast Artillery were used behind the lines. An outstanding French weapon was the 75-mm gun. Its superior recoil mechanism permitted rapid fire—a rate of 20 to 25 rounds (shots) a minute. The German Paris Gun (also called "Big Bertha") was an 8.4-inch (213-mm) gun that fired on Paris in 1918 from a distance of 75 miles (110 km), which hurled shells at 15 1/2 miles (24.9 kilometers) above the ground.

Antiaircraft guns used during World War I were mainly conventional artillery pieces on special mounts. After the war, efforts were directed toward developing guns better suited for use against airplanes. The greatest need was for automatic aiming and firing devices. An important development was radar tracking, which came into use in 1941.

World War II and After

By the beginning of World War II nearly all artillery was mechanized; that is, it was designed to be moved quickly from place to place by trucks or tractors. Tanks, which earlier had been armed only with machine guns, carried artillery weapons mounted in armored turrets. As the war progressed, large self-propelled guns came into use and rockets were reintroduced into warfare. Most of the rockets were short-range, small-caliber weapons. An exception was the German V-2, introduced in 1944 as a long-range bombardment missile. Perhaps the most versatile gun of the war was another German weapon—the 88-mm gun; it could be used on a tank, as an antiaircraft gun, or as conventional field artillery.

Fixed guns of the coast artillery type were little used in World War II, partly because it was a war of rapid movement and partly because the airplane proved a more effective weapon for long-range bombardment. On the other hand, the use of smaller weapons proved to be the greatest artillery advances during the war. The war also made use of helicopters to carry artillery into battle in a procedure known as airmobility. As a result, the U.S. Army abolished the Coast Artillery in 1950. All artillery units, including field artillery and antiaircraft artillery, were combined into a single arm. In 1952 the first missile units were added.

The Korean War (1950–53), after its opening stage, was fought from trenches, much like World War I. Artillery was used on a large scale with great precision.

After the Korean War, missiles were developed to such an extent that some consideration was given to abolishing guns entirely. In the guerrilla-type warfare of the Vietnamese War, however, the use of guns in close support of infantry proved to be of continuing effectiveness.

The United States fired the first atomic artillery shell from 280-millimeter cannon on May 29, 1953. Presently, atomic projectiles can be fired from the artillery weapons of smaller calibers.

In 1968 the U.S. Army separated air-defense units from ground-support artillery, creating two branches—Field Artillery and Air Defense Artillery.