Mortars have been used for hundreds of years, originally in siege warfare. Many historians consider the first mortars to have been used at the 1453 siege of Constantinople by Mehmed the Conqueror. A European account of the 1456 siege of Belgrade by Giovanni da Tagliacozzo said that the Ottoman Turks used seven mortars that fired "stone shots one Italian mile high". The time of flight of these was apparently long enough that casualties could be avoided by posting observers to give warning of their trajectories. However, earlier mortars were used in Korea in a 1413 naval battle when Korean gunsmiths developed the Wan'gu (gourd-shaped mortar) (완구, 碗口). The earliest version of the Wan'gu dates back to 1407. Choe Hae-san (최해산, 崔海山) (1380–1443), the son of Choe Mu-seon (1325–1395), is generally credited with inventing the first Wan'gu.
French mortar diagram from the 18th century.
Engraving depicting the Venetian siege of the Acropolis of Athens
, September 1687. The trajectory of the shell that hit the Parthenon, causing its explosion, is marked.
Early mortars, such as the Pumhart von Steyr, were also 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 (Siege of Grave, 1673). This mortar fired an exploding shell, which had a fuse lit by the hot gases when fired. This innovation was quickly taken up, 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 store in the Parthenon was blown up (see diagram).
An early use of these more mobile mortars as field (rather than siege) weapons 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.
1841 US Coehorn mortars, photographed in 1865
The mortar had fallen out of general use by the Napoleonic era and interest in the weapon was not revived until the beginning of the 20th century. However, mortars were heavily use by both sides during the American Civil War. At the Siege of Vicksburg, General US Grant reported making coehorn mortars "by taking logs of the toughest wood that could be found, boring them out for six- or twelve-pound 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".
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.
German 7.5 cm Minenwerfer,
The German Army studied the Siege of Port Arthur, where heavy artillery had been unable to destroy defensive structures like barbed wire and bunkers. As a result, they developed a short-barreled 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).
World War I also saw the introduction of the Stokes mortar. It was the first modern man-portable mortar and the forerunner of all modern mortars in use today. These modern weapons are light, adaptable, easy to operate, and yet possess enough accuracy and firepower to provide infantry with quality close fire support against soft and hard targets more quickly than any other means.