The list of units
The Hwach'a replaces the Cannon as the siege weapon of choice for the Korean civilization in the Middle Ages. The Hwach'a is a more advanced artillery unit, capable of bombarding adjacent targets and unlike other siege weapons it is even able to kill them rather than simply reducing their health. A Korean city must have saltpeter to build a Hwach'a.
Some of the first anti-personnel devices created in Korea were comprised of small rockets attached to arrows, which flung spikes upon detonation. When it was discovered that several of these rockets could be launched from the same container, larger versions of these anti-personnel devices were created and utilized in battle. These larger anti-personnel devices were designed to be transported on wheeled vehicles such as a two-wheeled carts and wheelbarrows. The Hwach'a, which was invented in 1451, allowed a single man to transport approximately 100 rockets into battle, and was well suited to combat the invading Japanese Samurai who typically advanced on the Koreans in dense groups, presenting ideal targets for the Hwach'a operators.