A mortar today is usually a simple, lightweight, man-portable, muzzle-loaded cannon, consisting of a smooth-bore (although some models use a rifled barrel) metal tube fixed to a base plate (to spread out the recoil) with a lightweight bipod mount and a sight. Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition. Historically mortars were heavy siege artillery. Mortars launch explosive shells (technically called bombs)[1] in high-arching ballistic trajectories.
Mortars have been used for hundreds of years. The earliest reported use of mortars was in Korea in a 1413 naval battle when Korean gunsmiths developed the wan'gu (gourd-shaped mortar) (완구, 碗口).[2] The earliest version of the wan'gu dates back to 1407.[3] Ch'oe Hae-san (1380–1443), the son of Ch'oe Mu-sŏn (1325–1395), is generally credited with inventing the wan'gu.[4] In the Ming dynasty, general Qi Jiguang recorded the use of a mini cannon called the hu dun pao that was similar to the mortar.[5]
The first use in siege warfare was at the 1453 siege of Constantinople by Mehmed the Conqueror. An Italian account of the 1456 siege of Belgrade by Giovanni da Tagliacozzo states that the Ottoman Turks used seven mortars that fired "stone shots one Italian mile high".[6] The time of flight of these was apparently long enough that casualties could be avoided by posting observers to give warning of their trajectories.[7]
Early mortars, such as the Pumhart von Steyr, were large and heavy and could not be easily transported. Simply made, these weapons were no more than iron bowls reminiscent of the kitchen and apothecary mortars whence they drew their name. An early transportable mortar was invented by Baron Menno van Coehoorn in 1701.[8][9] This mortar fired an exploding shell, which had a fuse that was lit by the hot gases when fired. The Coehorn mortar gained quick popularity, necessitating a new form of naval ship, the bomb vessel. Mortars played a significant role in the Venetian conquest of Morea, and in the course of this campaign an ammunition depot in the Parthenon was blown up. An early use of these more mobile mortars as field artillery (rather than siege artillery) was by British forces in the suppression of the Jacobite rising of 1719 at the Battle of Glen Shiel. High angle trajectory mortars held a great advantage over standard field guns in the rough terrain of the West Highlands of Scotland.
The mortar had fallen out of general use in Europe by the Napoleonic era, although Manby Mortars were widely used on the coast to launch lines to ships in distress, and interest in their use as a weapon was not revived until the beginning of the 20th century. Mortars were heavily used by both sides during the American Civil War. At the Siege of Vicksburg, General Ulysses S. Grant reported making mortars "by taking logs of the toughest wood that could be found, boring them out for 6 or 12 lb (2.7 or 5.4 kg) shells and binding them with strong iron bands. These answered as Coehorns, and shells were successfully thrown from them into the trenches of the enemy".[10]
During the Russo-Japanese War, Lieutenant General Leonid Gobyato of the Imperial Russian Army applied the principles of indirect fire from closed firing positions in the field; and with the collaboration of General Roman Kondratenko, he designed the first mortar that fired navy shells.
The German Army studied the Siege of Port Arthur, where heavy artillery had been unable to destroy defensive structures like barbed wire and bunkers. Consequently they developed a short-barrelled rifled muzzle-loading mortar called the Minenwerfer. Heavily used during World War I, they were made in three sizes: 7.58 cm (2.98 in), 17 cm (6.7 in), and 25 cm (9.8 in).
It was not until the Stokes mortar was devised by Sir Wilfred Stokes in 1915 during the First World War that the modern mortar transportable by one person was born. In the conditions of trench warfare, there was a great need for a versatile and easily portable weapon that could be manned by troops under cover in the trenches. Stokes' design was initially rejected in June 1915 because it was unable to use existing stocks of British mortar ammunition, and it took the intervention of David Lloyd George (at that time Minister of Munitions) and Lieutenant Colonel J. C. Matheson of the Trench Warfare Supply Department (who reported to Lloyd George) to expedite manufacture of the Stokes mortar. The weapon proved to be extremely useful in the muddy trenches of the Western Front, as a mortar round could be aimed to fall directly into trenches, where artillery shells, because of their low angle of flight, could not possibly go.[11]
The Stokes mortar was a simple muzzle-loaded weapon, consisting of a smoothbore metal tube fixed to a base plate (to absorb recoil) with a lightweight bipod mount. When a mortar bomb was dropped into the tube, an impact sensitive primer in the base of the bomb would make contact with a firing pin at the base of the tube and detonate, firing the bomb towards the target. The Stokes mortar could fire as many as 25 bombs per minute and had a maximum range of 800 yd (730 m), firing the original cylindrical unstabilised projectile.[12]
A modified version of the mortar, which fired a modern fin-stabilised streamlined projectile and had a booster charge for longer range, was developed after World War I;[13] this was in effect a new weapon. By World War II, it could fire as many as 30 bombs per minute and had a range of over 2,500 yd (2,300 m) with some shell types.[14] The French developed an improved version of the Stokes mortar as the Brandt Mle 27, further refined as the Brandt Mle 31; this design was widely copied with and without license.[15][16][17] These weapons were the prototypes for all subsequent light mortar developments around the world.
Mortar carriers are vehicles which carry a mortar as a primary weapon. Numerous vehicles have been used to mount mortars, from improvised civilian trucks used by insurgents, to modified infantry fighting vehicles, such as variants of the M3 half-track and M113 armored personnel carrier, to vehicles specifically intended to carry a mortar. Simpler vehicles carry a standard infantry mortar while in more complex vehicles the mortar is fully integrated into the vehicle and cannot be dismounted from the vehicle. Mortar carriers cannot be fired while on the move, and some must be dismounted to fire.
There are numerous armoured fighting vehicles and even main battle tanks that can be equipped with a mortar, either outside or inside of the cabin. The Israeli Merkava tank uses a 60 mm (2.4 in) mortar as a secondary armament. The Russian army uses the 2S4 Tyulpan self-propelled 240 mm (9.4 in) heavy mortar which is one of the largest mortars in current use.
Gun-mortars are breech-loaded mortars usually equipped with a hydraulic recoil mechanism, and sometimes equipped with an autoloader. They are usually mounted on an armoured vehicle and are capable of both direct fire and indirect fire. The archetypes are the Brandt Mle CM60A1 and Brandt 60 mm LR, which combine features of modern infantry mortars together with those of modern cannon. Such weapons are most commonly smoothbore, firing fin-stabilised rounds, using relatively small propellant charges in comparison to projectile weight. While some have been fitted with rifled barrels, such as the 2S31 Vena and 2S9 Nona. They have short barrels in comparison to guns and are much more lightly built than guns of a similar calibre – all characteristics of infantry mortars. This produces a hybrid weapon capable of engaging area targets with indirect high-angle fire, and also specific targets such as vehicles and bunkers with direct fire. Such hybrids are much heavier and more complicated than infantry mortars, superior to rocket-propelled grenades in the anti-armour and bunker-busting role, but have a reduced range compared to modern gun-howitzers and inferior anti-tank capability compared to modern anti-tank guided weapons. However, they do have a niche in, for example, providing a multi-role anti-personnel, anti-armour capability in light mobile formations. Such systems, like the Soviet 120 mm 2S9 Nona, are mostly self-propelled (although a towed variant exists). The AMOS (Advanced Mortar System) is an example of an even more advanced gun mortar system. It uses a 120 mm automatic twin-barrelled, breech-loaded mortar turret, which can be mounted on a variety of armoured vehicles and attack boats. A modern example of a gun-mortar is the 2B9 Vasilek.
A spigot mortar consists mainly of a solid rod or spigot, onto which a hollow tube in the projectile fits—inverting the normal tube-mortar arrangement. At the top of the tube in the projectile, a cavity contains propellant, such as cordite. There is usually a trigger mechanism built into the base of the spigot, with a long firing pin running up the length of the spigot activating a primer inside the projectile and firing the propellant charge. The advantage of a spigot mortar is that the firing unit (baseplate and spigot) is smaller and lighter than a conventional tube mortar of equivalent payload and range. It is also somewhat simpler to manufacture. Further, most spigot mortars have no barrel in the conventional sense, which means ammunition of almost any weight and diameter can be fired from the same mortar.
The disadvantage is that while most mortar bombs have a streamlined shape towards the back that fits a spigot mortar application well, using that space for the spigot mortar tube takes volume and mass away from the payload of the projectile. If a soldier is carrying only a few projectiles, the projectile weight disadvantage is not significant. However, the weight of a large quantity of the heavier and more complex spigot projectiles offsets the weight saved.
A near-silent mortar can operate using the