A howitzer is a type of artillery weapon used by militaries for land assaults. Traditionally, the size of this gun fell between a gun-type assault weapon and a larger mortar-type assault weapon. In the last century, however, especially in the United States, the term is generally used for a type of weapon more accurately described as a gun-howitzer. It has long played an important role in war, and its use is an important strategic decision for many military operations, as commanders are forced to choose between superior firepower and better mobility.
The modern version of this weapon dates back to the late-17th century, when the Swedes used them to great effect in their land battles to demolish the fortifications of enemies. This version was primarily differentiated from the mortar by its flexibility, as it could be shifted to attack at different angles, as opposed to mortars, which could attack only on a fixed arc. This meant that howitzers could be adjusted relatively easily, giving troops more precision in their attacks.
By the mid-19th century, the howitzer had evolved substantially. They were able to fire both cannonballs and explosive rounds, leading to the term gun-howitzer. They were also considerably more mobile than earlier guns, so that field infantry could bring them into battle and set them up on the fly. Field versions continued to become heavier and to have larger rounds, creating very heavy weaponry that could decimate walls and penetrate any intervening obstacles easily.
By World War I, the weapon had evolved even further, with longer barrels, higher velocities, and larger rounds. It saw a great deal of use during World War I, as their angle of attack lent them to trench warfare, where they could be fired from a trench and properly aimed to land in an enemy trench, exploding and causing massive damage. By World War II, the traditional version had largely been phased out, with the gun-howitzer replacing all but a few field guns.
There are a number of different types of howitzer, generally divided into groups based on the form of mobility. For example, a field howitzer is a one that can be brought into battle with field infantry, generally with some sort of carriage. A pack version is meant to be brought with field infantry in pieces, and then assembled at a place of battle. A siege version, on the other hand, is generally large enough it cannot easily be transported, and must be hauled into place by helicopter, and is then a semi-permanent installation. Finally, a self-propelled howitzer resembles a tank, as it is mounted on a motor vehicle and is often armored, but unlike a tank, it can shift its angle of attack.
Famous historical versions include the British QF 25 pounder from World War II, the M198 and M109 howitzers used by the United States in the latter part of the 20th century, and the G5 used in South Africa during the 1980s. Modern versions include the M777, transported to a site by helicopter; the self-propelled German PzH 2000, and the Singaporean SSPH Primus. In the United States military, the M777 is rapidly replacing the M198 for most field operations, and has seen significant action in Afghanistan.