The word gun includes most of the species of fire-arms; pistols and mortars being almost the only ones excepted from this denomination. They are divided into great and small guns; the former including what we commonly call cannon, ordnance, or artillery; the latter muskets, carbines, musketoons, blunderbusses, fowling-pieces, and the like. Great guns were those first used. They were originally made of iron bars soldered together, and fortified with strong iron hoops; some of which are still to be seen. Others were made of thin sheets of iron rolled up together and hooped; and on emergencies they were made of leather, with plates of iron or copper. These pieces were made in a rude and imperfect manner, like the first essays of many new inventions. Stone balls were thrown out of them, and a small quantity of powder was used, on account of the weakness of their construction. These pieces had no ornaments, were placed on their carriages by rings, and were of a cylindrical form. When or by whom guns were first made is uncertain. At the siege of Claudia Jessa, now called Chioggia, in 1366, the Venetians used cannon, which were brought thither by two Germans, with some powder and leaden balls; and they had likewise recourse to the same engines in their wars with the Genoese in 1379. Edward III. made use of cannon at the battle of Cressy in 1346, and at the siege of Calais in 1347. Cannon were employed by the Turks at the siege of Constantinople in 1394, and in that of 1452; these guns threw a ball of 100 lbs., but they generally burst at the first, second, or third discharge. Louis XII. had a cannon of the same size cast at Tours, which threw a ball from the Bastille to Charenton.

Formerly cannon were dignified with uncommon names. Gunlock. In 1503 Louis XII. had twelve brass cannon, of an extraordinary size, called after the twelve peers of France. The Spaniards and Portuguese named them after their saints. At present cannon take their names from the weight of the ball they discharge. Thus a piece which discharges a ball of twenty-four pounds is called a twenty-four pounder.

Mortars are supposed to have been fully as ancient as cannon. They were employed in the wars of Italy to throw balls of red-hot iron, stones, and the like, long before the invention of shells. The latter are believed to be of German invention, and the use of them in war was taught by accident. A citizen of Venlo, at a certain festival celebrated in honour of the Duke of Cleves, threw a number of shells, one of which fell on a house and set fire to it, by which misfortune the greater part of the town was reduced to ashes. The first account of shells used for military purposes is in 1435, when Naples was besieged by Charles VIII. History informs us with more certainty that shells were thrown out of mortars at the siege of Wachtendonk in Guelderland, in 1588. Malter, an English engineer, first taught the French the art of throwing shells, which they practised at the siege of Motte in 1634. The method of throwing red-hot balls out of mortars was first put in practice at the siege of Stralsund in 1675, by the elector of Brandenburg; though some say in 1653, at the siege of Bremen.

Muskets were first used at the siege of Rhege in the year 1521. The Spaniards were the first who armed part of their foot with these weapons. At first they were very heavy, and could not be used without a rest. They had matchlocks, and did execution at a great distance. On their march the soldiers carried only the rest and ammunition, and had boys to bear their muskets after them. They were very slow in loading, not only by reason of the unwieldiness of their pieces, and because they carried the powder and ball separate, but from the time it took to prepare and adjust the match. But a lighter matchlock-musket afterwards came into use; and the musketeers carried their ammunition in bandeliers, to which were hung several little cases of wood covered with leather, each containing a charge of powder. The balls were carried loose in a pouch, and a priming-horn was suspended by the side. The muskets with rests were used as late as the beginning of the civil wars in the time of Charles I. The lighter kind succeeded them, and continued till the beginning of last century, when they were also disused, and the troops throughout Europe armed with firelocks.