History of Cannon - Early Modern Period

Early Modern Period

By the 16th century, cannon were made in a great variety of lengths and bore diameters, but the general rule was that the longer the barrel, the longer the range. Some cannon made during this time had barrels exceeding 10 ft (3.0 m) in length, and could weigh up to 20,000 pounds (9,100 kg). Consequently, large amounts of gunpowder were needed, to allow them to fire stone balls several hundred yards. By mid-century, European monarchs began to classify cannon to reduce the confusion. Henry II of France opted for six sizes of cannon, but others settled for more; the Spanish used twelve sizes, and the English sixteen. Better powder had been developed by this time as well. Instead of the finely ground powder used by the first bombards, powder was replaced by a "corned" variety of coarse grains. This coarse powder had pockets of air between grains, allowing fire to travel through and ignite the entire charge quickly and uniformly.

The end of the Middle Ages saw the construction of larger, more powerful cannon, as well their spread throughout the world. As they were not effective at breaching the newer fortifications resulting from the development of cannon, siege engines—such as siege towers and trebuchets—became less widely used. However, wooden "battery-towers" took on a similar role as siege towers in the gunpowder age—such as that used at siege of Kazan in 1552, which could hold ten large-caliber cannon, in addition to 50 lighter pieces. Another notable effect of cannon on warfare during this period was the change in conventional fortifications. Niccolò Machiavelli wrote, "There is no wall, whatever its thickness that artillery will not destroy in only a few days." Although castles were not immediately made obsolete by cannon, their use and importance on the battlefield rapidly declined. Instead of majestic towers and merlons, the walls of new fortresses were thicker, angulated, and sloped, while towers became lower and stouter; increasing use was also made of earthen, brick, and stone breastworks and redoubts. These new defenses became known as "star forts," after their characteristic shape. A few of these featured cannon batteries, such as the Tudors' Device Forts, in England. Star forts soon replaced castles in Europe, and, eventually, those in the Americas, as well.

By end of the 15th century, several technological advancements were made, making cannon more mobile. Wheeled gun carriages and trunnions became common, and the invention of the limber further facilitated the transportation of artillery. As a result, field artillery became viable, and began to emerge, often used alongside the larger cannon intended for sieges. The better gunpowder, improved, cast-iron projectiles, and the standardization of calibers meant that even relatively light cannon could be deadly. In The Art of War, Niccolò Machiavelli observed that "It is true that the arquebuses and the small artillery do much more harm than the heavy artillery." This was the case at Flodden, in 1513: the English field guns outpaced the Scottish siege artillery, firing twice, or even thrice, as many rounds. Despite the increased maneuverability, however, cannon were still much slower than the rest of the army: a heavy English cannon required 23 horses to transport, while a culverin, nine, yet, even with this many animals transporting them, they still moved at a walking pace. Due to their relatively slow speed, and lack of organization, discipline, and tactics, the combination of pike and shot still dominated the battlefields of Europe.

Innovations continued, notably the German invention of the mortar, a thick-walled, short-barreled gun that blasted shot upward at a steep angle. Mortars were useful for sieges, as they could fire over walls and other defenses. This cannon found more use with the Dutch, who learned to shoot bombs filled with powder from them. However, setting the bomb fuse in the mortar was a problem. "Single firing" was the first technique used to set the fuse, where the bomb was placed with the fuse down against the propelling charge. This practice often resulted in the fuse being blown into the bomb, causing it to blow up in front of the mortar. Because of this danger, "double firing" was developed, where the fuse was turned up and the gunner lighted the fuse and the touch hole simultaneously. This, however, required much skill and timing, and was especially dangerous when the gun failed to fire, leaving a lighted bomb in the barrel. Not until 1650 was it accidentally discovered that double-lighting was a superfluous process: the heat of firing was enough to light the fuse.

Gustavus Adolphus of Sweden emphasized the use of light cannon and mobility in his army, and created new formations and tactics that revolutionized artillery. He discontinued using all 12 pounder—or heavier—cannon as field artillery, preferring, instead, to use cannon that could be manned by only a few men. One gun, called the "leatheren," could be serviced by only two persons, but was abandoned, replaced by 4 pounder and 9 pounder demi-culverins. These could be operated by three men, and pulled by only two horses. Also, Adolphus's army was the first to use a special cartridge that contained both powder and shot, which sped up loading, and therefore increased the rate of fire. Additionally, he pioneered the use of canister shot against infantry, which was essentially a can, filled with musket balls. At the time, for each thousand infantrymen, there was one cannon on the battlefield; Gustavus Adolphus increased the number of cannon in his army so dramatically, that there were six cannon for each one thousand infantry. Each regiment was assigned two pieces, though he often decided to arrange his artillery into batteries, instead. These were to decimate the enemy's infantry, while his cavalry outflanked their heavy guns. At the Battle of Breitenfeld, in 1631, Adolphus proved the effectiveness of the changes made to his army, in particular his artillery, by defeating Johann Tserclaes, Count of Tilly. Although severely outnumbered, the Swedes were able to fire between three and five times as many volleys of artillery without losing ground, due to their infantry's linear formations. Battered by cannon fire, and low on morale, Tilly's men broke rank, and fled.

Around this time also came the idea of aiming the cannon to hit a target. Gunners controlled the range of their cannon by measuring the angle of elevation, using a "gunner's quadrant." Cannon did not have sights, therefore, even with measuring tools, aiming was still largely guesswork.

In the latter half of the 17th century, the French engineer Vauban introduced a more systematic and scientific approach to attacking gunpowder fortresses, in a time when many field commanders "were notorious dunces in siegecraft." Careful sapping forward, supported by enfilading ricochet fire, was a key feature of this system, and it even allowed Vauban to calculate the length of time a siege would take. He was also a prolific builder of star forts, and did much to popularize the idea of "depth defense" in the face of cannon. These principles were followed into the mid-19th century, when changes in armaments necessitated greater depth defense than Vauban had provided for. It was only in the years prior to World War I that new works began to break radically away from his designs.