
For me, my entry is the Hwacha, a Korean anti-infantry weapon. Otherwise known as the "rocket cart", the Hwacha was comprised of a person-drawn wagon base, with 100+ tubes mounted vertically. These would be filled with rocket arrows (gunpowder-propelled arrows), the wagon would be positioned such that the 500-yard trajectory of the arrows would land them into advancing enemy armies, and then the Koreans got to watch the carnage from a safe distance. Here's a modern reconstruction firing:

And here's the YouTube of the Mythbusters testing the idea out, and being really, really impressed with the results.
Essentially, it's an anti-infantry version of the Katyusha, 500 years early.
Anyone else's ideas?












