- For the thrash metal band, see Artillery (band)
Historically, artillery refers to any engine used for the discharge of projectiles during war. The term also describes ground-based troops with the primary function of manning such weapons.
Continental Artillery crew from the American Revolution
The word as used in the current context originated in the Middle Ages. It comes from the Old French atellier meaning "to arrange", and attillement meaning "equipment". From the 13th century an artillier referred to a builder of any war equipment, and for the next 250 years the sense of the word "artillery" covered all forms of military weapons.
"Artillery" is a general term covering several varieties of large-calibre weapons; currently these fire an explosive shell or rocket and are of such a size and weight as to require a specialized mount for firing and transport. Weapons covered by this term in the modern era include "tube" artillery such as the howitzer, cannon, mortar, and field gun and "rocket" artillery. Older engines like the catapult, onager, trebuchet and ballista are also artillery but generally fired a solid shot.
The types of tube artillery are generally distinguished by their ballistic trajectory. Cannons (such as infantry support guns or the guns on a naval ship) are typically low-angle weapons designed for a direct-fire role. Mortars are high-angle weapons originally used to drop shells behind the walls of a city. Howitzers are capable of both high- and low-angle fire. They are most often employed in an indirect-fire role where they can be safe from enemy direct-fire weapons, operating in defilade.
Types of artillery:
- field artillery - mobile weapons used to support armies in the field. Subcategories include:
- infantry support guns - directly support infantry units (mostly obsolete).
- mountain guns - lightweight weapons that can be moved through difficult terrain.
- howitzers - capable of high angle fire.
- gun howitzers - capable of high or low angle fire with a long barrel.
- mortars - lightweight weapons that fire projectiles at an angle of over 45 degrees to the horizontal.
- self-propelled artillery - typically guns, mortars or gun howitzers mounted on a vehicle.
- naval artillery - cannons mounted on warships and used either against other ships or in support of ground forces.
- coastal artillery - Fixed-position weapons dedicated to defense of a particular location, usually a coast (e.g. the Atlantic Wall in WW 2) or harbor. Not needing to be mobile, coastal artillery can be much larger than equivalent field artillery pieces, giving them longer range and more destructive power. Since World War II, however, modern weapons and tactics have made them largely obsolete.
- anti-aircraft artillery - weapons, usually mobile, dedicated to attacking aircraft from the ground.
All forms of artillery require a propellant to fire the projectile at the target. A number of different configurations have been developed, each with varying characteristics. They include:
- Tube fired - utilise the pressure of burnt propellant inside a barrel to force a projectile out of the mouth of the barrel.
- Spin stabilised - Use helical grooves or ridges on the inside of the barrel to impart a rotation to the projectile as it is travelling in the barrel.
- Fin stabilised - Use fins at the rear of the projectile in the airflow to maintain correct orientation.
- Inverted tube - Some weapons have been built with the tube built into the projectile and fitted onto a rod fitted to the carriage.
- Recoilless - A tube fired weapon with a breech designed to perforate a bursting disk at firing, and permit a mass of burnt propellant gases with momentum equal to the projectile to exit from the rear of the barrel, to prevent recoil from affecting the weapon.
- Rocket propelled - Tube or rail launched - A reaction propulsion system mounted to the projectile provides continuous thrust for an initial period of the flight.
- Rocket assist - A combination of tube fired and rocket propelled - uses a rocket motor in the base of the projectile to extend the range by about 30%.
- Base bleed - Similar to a rocket assist projectile, uses a small pyrotechnic charge at the base of the projectile. The charge introduces sufficient combustion products into the low-pressure region behind the base of the projectile responsible for a large proportion of the drag to substantially (> 30%) increase range. Like a rocket assist projectile, trajectory is changed to non-ballistic, which may complicate counter-battery location.
The term "artillery" has traditionally not been used for projectiles with internal guidance systems, even though some artillery units employ surface-to-surface missiles. Recent advances in terminal guidance systems for small munitions has allowed large calibre shells to be fitted with precision guidance fuses, blurring this distinction.
Roles of the artillery
Depending on the calibre of the weapons, artillery is used in a variety of roles. Mortars fire relatively short range and small- to medium-calibre (up to about 120 mm) projectiles in a high arc against targets that cannot be reached by low-angle (less than 45 degrees) fire, such as troops on the reverse slope of a hillside. Modern mortars, because of their lighter weight and simpler, more transportable design, are usually organic to infantry and armor units, allowing greater responsiveness and negating their shorter range.
Howitzers are longer ranged weapons that generally fire in a flatter arc - the target is seldom in view of the firer. Howitzers are generally used in direct support of infantry and armor, where the guns of a battery or even a battalion will be massed to fire simultaneously onto a single point or area target. Howitzers are usually beteen about 105 mm and 155 mm in calibre.
Attacks aimed at enemy artillery rather than infantry or fortifications are known as Counter Battery Fire. Modern artillery units have radar systems able to track enemy artillery fire, calculate its source and fire upon that source. When artillery fire is directed via radio by a forward observer (FO), the location of FO's transmitter can be calculated and attacked with artillery as well. If successful, this counter-attack will limit the effectiveness of the FO's artillery fire.
Modern field artillery falls into two categories: towed and self-propelled. As the name implies, towed artillery has a prime mover, usually a jeep or truck, to move the piece, crew, and ammunition around. Self-propelled howitzers are permanently mounted on a carriage or vehicle with room for the crew and ammunition and capable of moving independently in order to move quickly from one firing position to another - to both support the fluid nature of modern combat and to avoid 'counter-battery fire'. There are also mortar carrier vehicles, many of which allow the mortar to be removed from the vehicle and be used dismounted, potentially in terrain the vehicle can't get to or in order to avoid immediate detection.
The field artillery team
Modern field artillery (Post-World War I) has three distinct parts: the forward observer (or FO), the fire direction center (FDC) and the actual howitzers themselves. Because artillery is an indirect fire weapon, the forward observer must take up a position where he can observe the enemy using tools such as binoculars and laser range finders and designators and call back fire missions on his radio. This position can be anywhere from a few thousand meters to 20-30 km distant from the guns. Using a standardized format, the FO sends either an exact target location or the position relative to his own location, a brief target description, a recommended munition to use, and any special instructions such as "danger close" (the warning that friendly troops are within 600 metres of the target, requiring extra precision from the guns). The FO does not talk to the guns directly - he deals solely with the FDC. The forward observer can also be airborne and in fact one of the original roles of aircraft in the military was airborne artillery spotting.
Typically, there is one FDC for a battery of six guns. The FDC computes firing data for the guns. The process consists of determining the precise target location based on the observer's location if needed, then computing range and direction to the target from the guns' location. These data can be computed manually, using special protractors and slide rules with precomputed firing data. Corrections can be added for conditions such as a difference between target and howitzer altitudes, propellant temperature, atmospheric conditions, and even the curvature and rotation of the Earth. In most cases, some corrections are omitted, sacrificing accuracy for speed. In recent decades, FDCs have become computerized, allowing for much faster and more accurate computation of firing data.
The final piece of the puzzle is the "gun line" itself. The FDC will transmit the fire order to the howitzers, specifying the number of volleys, a particular shell and fuze combination, the specific charge, a deflection (horizontal direction) and quadrant elevation (vertical direction) both specified in mils, and any special instructions, such as to wait for the observer's command to fire relayed through the FDC. The crews load the howitzers and traverse and elevate the tube to the required point, using either hand cranks (usually on towed guns) or hydraulics (on self-propelled models).
It is actually possible for very modern computer-controlled artillery to fire more than one volley at a target and have all the shells arrive simultaneously. This is because there is more than one trajectory for the rounds to fly to any given target - typically one is below 45 degrees from horizontal and the other is above it, and if you can vary the amount of propellant with each shell, you can create more trajectories. Because the higher trajectories cause the shells to arc higher into the air, they take longer to reach the target and so if the shells are fired on these trajectories for the first vollies (starting with the shell with the most propellant and working down) and then after the correct pause more vollies are fired on the lower trajectories, the shells will all arrive at the same time. This is useful because many more shells can land on the target with no warning. With traditional volleys along the same trajectory, anybody at the target point will have a certain amount of time (however long it takes to reload and re-fire the guns) to run away or take cover between volleys. This technique is known as MRSI (Multiple Rounds Simultaneous Impact). In addition, if guns in more than one location are firing on one target, with careful timing it can be arranged for all their shells to land at the same time for the same reason.
Examples of MRSI guns are South Africa's Denel G6-52 (which can land six rounds simultaneously at targets at least 25 km away) and Germany's Panzer Haubitze 2000 (which can land five rounds simultaneously at targets at least 17 km away). The United States Crusader programme (now cancelled) was slated to have MRSI capability.
Radar has had a major impact on artillery. Coupled to computers it can accurately track a projectile in flight back to its firing point. This can be used as targeting information for 'counter-battery fire' - artillery bombardment of an enemy artillery site. Radar improves the ability to return fire quickly and accurately. This greatly increases the all-weather flexibility of modern artillery. The rise in counter-battery abilities drove the field artillery to adopt 'shoot-and-scoot' tactics emphasizing constant maneuver within an designated position area, usually from hide point to firing point and back again. This has required reliance on sometimes temperamental technology and increased the cost of modern field artillery systems.
- I do not have to tell you who won the war. You know, the artillery did. - Gen George S. Patton
- "Our artillery... The Germans feared it almost more than anything we had." - Ernie Pyle "Brave Men", AD 1944
- Artillery is the god of war. - Stalin
- "Contrary to popular belief, we at artillery command do not believe we're God. We merely borrowed his "Smite" button." - Anonymous
- The Mission of the Artillery is to give some class to what would otherwise be merely a vulgar brawl. - Some Redleg.