Field artillery

Field artillery is a category of mobile artillery used to support armies in the field. These weapons are specialized for mobility, tactical proficiency, long range, short range and extremely long range target engagement.

Until the early 20th century, field artillery were also known as foot artillery, for while the guns were pulled by beasts of burden (often horses), the gun crews would usually march on foot, thus providing fire support mainly to the infantry. This was in contrast to horse artillery, whose emphasis on speed while supporting cavalry units necessitated lighter guns and crews riding on horseback.

Whereas horse artillery has been superseded by self-propelled artillery, field artillery has survived to this day both in name and mission, albeit with motor vehicles towing the guns, carrying the crews and transporting the ammunition. Modern artillery has also advanced to rapidly deployable wheeled and tracked vehicles and precision delivered munitions capable of striking tarkets at ranges between 15 and 300 kilometers. There exists to date no other singularly effective all weather fires delivery system which rivals the modern field artillery.

Types

Field guns - capable of long range fire
Gun howitzers - capable of high or low angle fire with a long barrel
Howitzers - capable of high angle fire
Infantry support guns - directly support infantry units (mostly obsolete)
Mortars - lightweight weapons that fire projectiles at an angle of over 45 degrees to the horizontal
Mountain guns - lightweight weapons that can be moved through difficult terrain
Multiple rocket launchers - Mobile rocket artillery Launchers

American artillery crew during the Revolutionary War.

History

Early Modern era

Early artillery was unsuited to the battlefield, as the extremely massive pieces could not be moved except in areas that were already controlled by the combatant. Thus, their role was limited to such functions as breaking sieges.^[1] Later, the first field artilleries came into function as metallurgy allowed thinner barrels to withstand the explosive forces without bursting. However, there was still a serious risk of the constant changes of the battlefield conspriring to leave behind slow-moving artillery units - either on the advance, or more dangerously, in retreat.^[1] In fact, many cavalry units became tasked with destroying artillery units as one of their main functions.^{[citation needed]}

Only with a number of further inventions (such as the limber, hitched to the trail of a wheeled artillery piece equipped with trunnions), did the concept of field artillery really take off.^[1]

20th Century

Before the first World War, field artillery batteries generally fired directly at visible targets measured in distances of meters and yards. Today, modern field batteries measure targets in kilometers and miles and often do not directly engage the enemy with observed direct fire. This hundredfold increase in the range of artillery guns in the 20th century has been the result of development of rifled cannons, improvements in propellants, better communications between observer and gunner and technical improvements in gunnery computational abilities.

Most field artillery situations require indirect fire due to weather, terrain, night-time conditions, distance or other obstacles. These gunners can also rely upon a trained artillery observer, also called a forward observer who sees the target, relays the coordinates of the target to their fire direction center which, in turn translates those coordinates into: a left-right aiming direction; an elevation angle; a calculated number of bags of propellant and finally a fuze with a determined waiting time before exploding, (if necessary) to be set, which is then mated to the artillery projectile now ready to be fired.

Field artillery team

Modern field artillery (Post-World War I) has two distinct parts: some forward observers (or FOs), and the batteries. Each battery is divided into the fire direction center (FDC) and the actual guns themselves.

The FOs sit forward where they can see the targets and call fire upon them. They signal the FDC of the battery, who calculate the gun settings, tell the guns, who then fire. The FO observes the fall of shot and sends correcting signals.

The batteries are many kilometres behind the FEBA, so one might hope well away from enemy infantry. They pick a "convenient" location where they can sit for some while and do multiple firemissions before needing to relocate.

In normal operations the FOs locate targets and signal them to the FDCs.

They can also calculate "defensive fire" tasks. These are pre-planned missions, typically just in front of or upon ones own positions. Because the calculations have already been done, the fire can be called down very quickly when it is needed. Dropping fire just in front of ones positions aims to suppress an attack. If ones postion has to be abandoned then fire can be dropped upon that location to prevent the enemy from consolidating their position.

FO (Forward Observer)

Because artillery is an indirect fire weapon, the forward observer must take up a position where he can observe the target using tools such as binoculars and laser rangefinders and call back fire missions on his radio/telephone.

The FO usually sits on the ground in cover, from which he can see the enemy. However he may also be airborne, which was the original use of aircraft in WWI. He must take great care not to be observed by the enemy, especially if in a static position. Once they find his location they can take offensive action against him; this is not only bad for him but also for the ability of the battery to lay fire.

Using a standardized format, the FO sends map ref. and bearing to target, 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 meters of the target when using artillery, requiring extra precision from the guns).

The FO and the battery iteratively "walk" the fire onto the target. The FDC signals the FO that they have fired and the FO knows to observe fall of shot. He then signals corrections. These are normally of the form of left/right of the bearing line and distance along it, for example "right 50 add 100" (distance in metres). When the fire is good enough the FO signals "target on, fire for effect".

If the mission requires "walking fire" he may continue sending correction orders.

The FO may be called upon to direct fire for CAS and/or Naval GunFire in addition to Field Artillery based howitzer and Infantry based mortar units.

The US Army Field Manual describing the duties and responsibilities is FM 6-30, Tactics, Techniques, and Procedures for Observed Fire.

File:785px-Arty Call for Fire 1.jpg

Calling in and adjusting artillery fire on a target visible to a forward observer but not to the soldiers manning the guns, themselves

FDC (Fire Direction Center)

Typically, there is one FDC for a battery of six guns, in a light division. In a typical heavy division configuration, there exist two FDC elements capable of operating two four gun sections, also known as a split battery. The FDC computes firing data, fire direction, 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 FDC at the battalion level is responsible for recording friendly and enemy positions, tracking available battery munitions, and determining the optimal response for engaging a target identified by the FO.

CP

In most Artillery Batteries the Command Post or CP controls the firing of the guns. It is usually located at the battery center so as to be able to communicate easily with the guns. The CP should be well camouflaged, but the CPO (Command Post Officer) should be able to see all the guns with ease. Gun markers are sometimes placed in front of the CP to remind the CPO which gun is in which position. The CPO is assisted by two "Acks" - or assistants - who operate the fire data computers. The GPO (Gun Position Officer) and CPO work at the plotter to ensure that the data calculated by the Acks is accurate and safe. The CP signaller is contact with the OP, or Observation Post, where the FOO, or Forward Observer Officer, works with the OP team to identify targets and call-back fire data. In recent years, headset radios have become common for communication between the CPO and gun detachment commanders.

Guns

The final piece of the puzzle is the "gun line" itself. The FDC will transmit a warning order to the guns, followed by orders specifying the type of ammunition and fuze setting, bearing, elevation, and the method of adjustment or orders for fire for effect (FFE). Elevation (vertical direction) and bearing orders are 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 barrel to the required point, using either hand cranks (usually on towed guns) or hydraulics (on self-propelled models).

Counter Battery

The enemy guns are a threat so one must attempt to remove them. Most of the time they are too far back for the infantry to engage, so it is left for the artillery.

They locate the enemy batteries and fire to remove them.

The battery uses a variety of techniques to calculate the position of the enemy battery, then can lay fire upon it. If one is lucky one can get an FO into position; either on the ground or in the air. Or one can use Counter-battery radar to locate their guns.

The radar watches the shell's flight and calculates the trajectory. This set of points will include the point on the ground from which the shell originated; i.e. from where it was fired. This location can be passed to the battery commandpost as a firemission.

Counter-counter Battery

To defend against counter battery fire there are two points of attack: either remove the enemy's ability to observe or make his observations irrelevant/obsolete.

To remove the ability to observe one must attack the observation assets. Because most counter-battery radar is active, the location can be determined electronically from listening to their beams. If one suspects ones position is being observed by a covert FO then a mission, either artillery or infantry, will be raised to deal with this threat.

Alternatively one can choose to make their observations obsolete by repeatedly moving the guns: hence self-propelled guns.

Ordinary towed guns can take a while to emplace and re-limber and are not armoured, so they are vulnerable to counter battery fire and take a while to engage when at a new location.

SP guns don't suffer from these restrictions. They can drive up, drop their trails, fire and move on. Because of their armour they are less vulnerable to counter-battery fire. But note that this armour is light by comparison to that of a tank, so it only protects from light fire (MGs) and splinter.

The downside to SP guns is that they tend to be a) have a lighter gun b) less accurate. Which is the most important advantage/restriction depends on how mobile a battle that is being fought.

Parent battalion and US Army brigade/USMC regimental FDCs

FDCs also exist in the next higher parent battalion that "owns" 2-4 artillery batteries. Once again, an FDC exists at the US Army brigade or USMC regimetal level that "owns" the battalions. These higher level FDCs monitor the fire missions of their subordinate units and will coordinate the use of multiple batteries or even multiple battalions in what is called a battalion or brigade/regimental mission. In training and wartime exercises, as many as 72 guns from 3 battalions may all be coordinated to put "steel on the target" in what is called a "brigade/regimental time on target" or brigade/regimental TOT for short. The rule is "silence is consent," meaning that if the lower unit does not hear a "cancel the mission" (don't shoot) or even a "check firing" (cease firing) order from the higher monitoring unit, then the mission goes on. Higher level units monitor their subordinate unit's missions both for active as well as passive purposes. Higher level units also may get involved to coordinate artillery fire across fire support coordination boundaries (often parallel lines on maps) where one unit can not fire into without permission from higher and/or adjacent units that "own" the territory.

Quotes

"Ultima ratio regum" English: "The final argument of kings" - Louis XIV's inscription on French artillery
"Do not forget your dogs of war, your big guns, which are the most-to-be respected arguments of the rights of kings." - Frederick II of Prussia
"The artillery lends honor to that which would otherwise be a vulgar brawl." - Frederick II of Prussia
"God is on the side with the best artillery." - Napoleon I of France
"The first shot is for the Devil, the second for God, and only the third for the King." - Napoleon I
"The best generals are those who have served in the artillery." - Napoleon I
"I do not have to tell you who won the war. You know, the artillery did." - General George S. Patton, Jr.
"Brother, your best friend ain't your Momma, it's the Field Artillery." - A sign at Fort Benning, US Infantry School
"The Guns, thank God, the Guns." - Rudyard Kipling
"Renown awaits the commander who first restores artillery to its prime importance on the battlefield." - Sir Winston Churchill
"Artillery is the god of war." Joseph Stalin

Major artillery battles

References

^ ^a ^b ^c A History of Warfare - Keegan, John, Vintage 1993

McFarland, Lieutenant Colonel Earl. Textbook of Ordnance and Gunnery John Wiley & Sons, Inc. New York, 1929.

[WARKEEGAN-1] A History of Warfare - Keegan, John, Vintage 1993

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