forsyth

Before 1798, literally everything was hand made. You had a bolt... well, there was one single nut in the whole world that would fit it properly!

Eli Whitney, widely known as the inventor of the cotton gin, also invented the whole concept of mass manufacturing. There's a story of him being given money by Congress to mass produce gun parts... he showed up with a bag of parts, dumped them on the floor, and proceeded to put together guns using random parts on the spot! They were all blown away, of course... and that single move changed the face of, not only war, but the entire planet.

It's hard to think of any single person that has had a greater impact on the planet.