[evan_au]

The rocket.
- Developed by the Chinese as a weapon
- Commemorated in the US national anthem ("the rocket's red glare")
- Improved in the early 1900s with improved fuels and nozzles
- Significantly advanced by Germany in WW2
- Now has some more productive uses for launching communications satellites, weather satellites and space probes

[Bored chemist]

For fairly loose definitions of "military" and "cool"
https://edition.cnn.com/videos/business/2018/10/16/robot-dog-spot-dancing.cnn-business