Gunpowder

Perhaps the only thing that saved alchemists from going extinct, much to the displeasure of the Church.

The only reliable means of making a big "boom" known to date, gunpowder is crucial to any nation's military and increasingly important to the profitability of certain businesses such as mining. Its history is particularly interesting as it perfectly illustrates how short-lived people's memory can be, when needed. Make one person benefit of it and they shall forget their morals; make a whole nation benefit of it and they shall forget their history. Give it time and the priests shall forget their preachings.
For many people, guns and cannons are symbols of Eire's might and its times of glory. Long lines of Eirish infantry, moving as one and sowing fear among the crumbling ranks of Empire's forces. Brave explorers and settlers, fighting off Vurradian raids of savages with spears and bows. The proud ships, with sun glistening on their dozens of cannons. All of it made possible by a single invention - a humble powder. Some people may remember its original name of a "Chaos's powder" and the Church's fury about it. Few will remember that gunpowder is in fact invention not of the Old World but of the New World.

Discovery

It was during their first expeditions further into the ocean that Eirish came upon the tribes of people they have never met before - the Vurradians. The explorers were peaceful at first, and their leader was once offered an honour to hunt together with the tribe's chief. It was during that hunt that the chief, perhaps in an attempt to impress the traders, first used a strange device capable of inflicting grave wounds with lighting and smoke. Perhaps, that was the true reason for the explorers' docile behaviour in dealing with the tribe. Such weapons were not rare among the warriors, yet they were rarely used. The chief explained that each "gun" took a very long time making, and a special mixture was required. Much labour had to be used to extract just a little bit of the mixture's key ingredient - saltpeter - from the soil.
The explorers eventually left, having laden their ships with goods bartered with the locals. Among them was one of the tribe's old guns and a small pouch of the powdered mixture. The tales told and the demonstration of the weapon's effectiveness was enough to gain the High King's support for another expedition, much less peaceful this time. The island was looted and its craftsmen taken back to the Wellimbrook Archipelago, where alchemists and smiths worked tirelessly to recreate the mixture and to create new types of weapons. The invention of new methods for producing large amounts of saltpeter and mass-manufacture of guns by professional smiths led to guns soon becoming increasingly commonplace, to the bitter fate of their original inventors.