Cannons

"My son John was tall and slim And he'd a leg for ev'ry limb. But now he's got no legs at all For he ran a race with a cannon ball" - Lyrics from a Vaegir Folk Song

Cannons do exist on the continent of Calradia, but they are incredibly rare. All known cannons were produced in the imperial forges at Myzea, long before the civil war. Large amounts of the highest quality ores required to forge something of the size needed to make such a weapon economical. In addition, in order to keep the metal from splitting under the massive pressure that is created, the metal has to be bound be dozens of metal rings that carry powerful enchantments that act as reinforcements. These enchantments must also be maintained over time, which is costly in manpower and resources.
When these beasts of war work though, they can often sway battles in the favour of those who hold them. Their projectiles are so large that they can often carry frightening amounts of alchemist's fire, alchemist's powder, or even pre-powered spells that can decimate thousands of soldiers in a single strike. Some cannons had even been modified for specific tasks, such as flame cannons that could fire torrents of alchemists fire over only 500m, but would guarantee the destruction of everything in that area, or cannons that could be angled upwards which were used to fight dragons, but were later used to lob munitions over the walls of a city onto the inhabitants within. 
Due to the difficulty in moving them, they are usually employed in sieges on both sides, to destroy walls, or to destroy attackers before they have the chance to reach fortifications. This also means both sides have the time to bring up wizards, smiths, and the resources required to maintain and re-load them in relative safety. 
Since the beginning of the Third Age, the once mighty armoury of imperial cannons alongside the old imperial artillery corps has been dispersed throughout the continent, and reduced significantly in size. Whereas in the days of old, the Calradian empire may have fielded hundreds of cannons, today only Eighteen are known to exist.
Below are the known/suspected locations of the cannonry of the old empire:
4 - The Western Calradian Empire 6 - The Eastern Calradian empire 2 - The Southern Calradian Empire 1 - The Battanian Confederacy  2 - The Kingdom of the Swadians  1 - The Aserai Confederacy 1 - Tsardom of the Vaegirs  1 - Unknown, confirmed missing from an armoury of the The Southern Calradian Empire

Manufacturing

No new cannons have been manufactured in Myzea for decades for numerous reasons. Chief among them is the cost, as the The Eastern Calradian empire no longer can bare the strain in resources to upkeep more than they currently own, and do not want any more to fall into the hands of their enemies. for these reasons, only 2 individuals remain who know the secrets of cannon production, one forgemaster and one enchanter. These individuals are a closely held state secret, as all others were executed, for fear that they would flee to other nations and produce more cannons for money.

Social Impact

Cannons are a thing that stories are told about by war veterans of all nations (whether they actually saw one or not). Even the idea of being on the other end of a cannon is a fear-inspiring concept, and many folk stories and songs have sprung up, started by those who have had to be on the other end of their wrath and lived.

Complexity

Cannons are, despite looking very simple, are incredibly complex to operate. Master cannoneers are required, that have been trained for decades to know everything about their weapon, so that they can use it without either destroying it or everyone around them.  
Cannoneers are trained to know the intertwined effects of the air, wind, rain, winds of magic, ground strength, munitions load, and propellant, to ensure that the cannon will fire as intended every time. A cannon misfire can quickly become the doom of the force attempting to utilize it.