In the 14th century, what was the greatest Chinese invention and why?

Water wheels. It enables hydralic powers be harnessed in silk spinning mill, irrigations, blast furnace, rice grinding mills etc. It increases productivities across industries.

One of the greatest inventions of the medieval world was the mechanical clock. The difficulty in inventing a mechanical clock was to figure out a way in which a wheel no bigger than a room could turn at the same speed as the Earth, but still be turning more or less continuously. If this could be accomplished, then the wheel became a mini Earth and could tell the time.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.