How do you work out something nobody will teach you?

That time, that place

At the end of Goryeo, raiders from the sea were sweeping the coast — coming in by ship, carrying off grain and people. By the time you met them on land, they were already aboard.

Stopping them at sea meant a weapon you could fire from a ship. That meant gunpowder.

China knew how to make it and would not say how. What Korea had was small quantities of the finished product.

Why this question

Gunpowder is three things mixed: charcoal, sulphur and saltpetre.

The first two are not hard to get. Saltpetre was the problem. It is not a mineral you dig. It gathers slowly in the soil under old floorboards, around hearths, in the floors of animal pens. You collect that soil, leach it, boil it down, filter it again, and crystallise what is left.

Which soil, how many leachings, what to add so the impurities settle — all of it is knack. Without someone telling you, there is no way in.

Choe Museon got the knack out of Yi Won, a Yuan merchant passing through Gaegyeong. The records say he asked and hosted him over a period of years.

What was found

In 1377 an office was set up to make gunpowder and firearms. What came out of it was not a few finished weapons but a system: cannon and fire-arrows, mountings, and the way to carry them on a ship.

In 1380 at Jinpo a fleet of some five hundred raider ships was met and burned by cannon fired from Korean vessels — an early instance anywhere of gunpowder weapons used from ships in an organised way.

What he had obtained was not a weapon but a method. Finished goods are used up; a method is not. He wrote his down and left it to his son, and Joseon went on improving firearms from there.

Terms on this card

Saltpetre