The discovery of gunpowder, which, by degrees, totally changed military tactics and the constitution of armies, was the event that most powerfully influenced warfare in the Middle Ages. Very little is known about its actual invention. It is supposed that Greek fire, which was used with such terrifying and destructive effect in warfare, particularly in sieges, consisted of the three ingredients of gunpowder, with resin and naphtha in addition.

Roger Bacon, an English friar, discovered the secret of the composition of gunpowder in the latter half of the 13th century; but Schwartz, a Franciscan, at Cologne, perfected it about a century later.

The use of cannon for siege purposes commenced in England in the armies of Edward III. Froissart says that the English army used them against Calais, when besieging it in 1347. But there were very few made at first; an important fortress like the Tower of London, in 1360, only mounting four guns, while Dover Castle, in 1372, had six.

When first introduced, cannon were small and vase-shaped; they were slow in fire, and very liable to accidents.

They were called “bombards,” and were mounted upon a wooden cradle or frame. Towards the end of the 14th century, they had become of large dimensions, firing heavy stone shot of from 200 to 450 lbs. weight. All the shot were stone until, because they did not do sufficient damage in battering down a wall, it became the practice to bind and otherwise strengthen them with iron.

The earliest cannon were of the rudest possible description. They were made of bars or thin sheets of iron, arranged longitudinally over a wooden core, in the form of a tube, around which were welded iron hoops to hold them together.

In 1338 there existed breech-loading guns, with one or more movable chambers, to facilitate loading, but, even then, the fire was very slow; “three shots an hour was fair practice for a big bombard.” It is not certain when wheeled carriages were introduced, though mention is made of two-wheeled bombard carriages in 1376; but it must be remembered that the gun at first was looked upon as a substitute for the balista and other war machines employed in the siege of a fortified place. Its value as an effective and movable weapon on the battlefield was not realised for some time.

The powder was fired at first by the insertion of a red-hot wire, but this was often very dangerous to the gunners, because the gun was so liable to burst. James II. of Scotland was killed by the bursting of a gun at the siege of Roxburgh in 1460. It became the custom, in the case of large bombards, for a small train of powder to be laid from the ground leading to the touchhole. The gunners fired the train, and then hastily betook themselves to a place of safety.

The earliest known representation of a gun in England is contained in a MS., “De Officiis Regum,” at Christ Church, Oxford, of the time of Edward II. (1326). It shows a knight in armour, firing a short, primitive weapon, shaped something like a vase, and loaded with an incendiary arrow—that is, one charged with an inflammable substance. Firearms of this type were evidently very small, as only 2 lb. of gunpowder was provided for firing forty-eight arrows.

From the beginning, contrivances had been made to resist the recoil of the gun when it was fired; heavy timbers, etc., were packed up against the breach to prevent the gun from flying backwards, but this plan often brought about the bursting of the gun. About the middle of the 15th century, trunnions (small cylinders of solid metal projecting from the sides, at right angles to the axis of the gun) were formed with the gun, and by means of these the recoil of the gun could be transferred to the carriage, and the pivoting of the gun up and down on the trunnions made the laying and sighting an easier task.

Stone cannon shot were employed until 1520, and, when it was considered necessary to use very heavy projectiles, correspondingly enormous guns had to be built. Mons Meg, a well-known gun in Edinburgh Castle, of this large type, is a wrought-iron gun of the 15th century. It is built of iron bars and external rings, with a calibre of 20 inches, and it fired a shot weighing 350 lbs.

Bronze guns, of a great size, were cast in 1468 at Constantinople, and one of them is now in the Rotunda at Woolwich. It was actually used in warfare against the English at the Dardanelles, in 1807. To show the destructive power of such a large piece of ordnance, even though a crude and ancient construction, it may be mentioned that the stone shot, weighing 700 lbs., which was fired from it against the English fleet, cut the mainmast of the British flagship in two, and another killed and wounded sixty men. These old 15th century guns in the battle altogether accounted for six of our men-of-war damaged and 126 men killed and wounded. The gun at Woolwich is in two pieces screwed together. The front part has a calibre of 25 inches for the reception of the shot, and a rear portion, forming a powder chamber, 10 inches in diameter. The whole gun weighs nearly 18¾ tons, and was presented to Queen Victoria by the Sultan of Turkey.

Late in the 15th century, guns began to be more regularly employed on the battlefield. In the 16th century, the extremely large guns were discarded, and small, wrought-iron guns were made, this change being due to the use of cast-iron shot, which was as destructive as the more bulky stone shot formerly used.

In 1521 the first bronze gun was cast in England, cast-iron cannon being made also in 1540, by foreign workmen, introduced into this country by Henry VIII. to teach the English the art. The first foundry was at Uckfield, in Sussex, and Sussex iron was used, smelted with charcoal.

The small gun of this period was made very long, and a specimen is to be found in Dover Castle. It is known as Queen Elizabeth’s Pocket Pistol, and is 24½ feet long, with a bore of 4¾ inches. It was cast in 1544, and was presented to Henry VIII. by Charles V.

Generally speaking, the English were much behind other nations in the use of artillery until the end of the 18th century. The quality of the gunpowder used in the early days of the cannon was very poor. The ingredients were often mixed on the spot at the time of loading, and the powder burnt slowly, with but little strength, and naturally varied from round to round. When the more fiercely-burning granulated powder was introduced into England, in the middle of the 15th century, it was often too strong for the larger pieces of that date, and could only be used for small firearms for more than a century afterwards.

In the 17th century, bronze and cast-iron guns were strengthened, and were more adapted to the use of grained powder, and, at the same time, more energy and greater range were obtained.