The Haber Process

Once upon a time, there was a German chemist named Fritz Haber. He had a process that could extract nitrogen from air, hydrogen from water, (but more likely from fossil fuels, because electrolysis of water is an expensive undertaking), and combine them into ammonia. It was kind of slow, and mostly a novelty. The net reaction was:

2N₂ + 3H₂ => 2NH₃

Then one day, a representative of the German government came to his office.
"Dr. Haber! Dr. Haber! The Fatherland needs your help!"
"What? How?"
"You know how we're fighting the great war? (The one the future would know as "World War I," but it wasn't known then that it would involve pretty much the whole world, nor that there would be a sequel.) England has cordoned off our supply of seagull poop!"
"Uhuh, remind me why you'd want that."
"Don't you see? It's our only source of ammonia! With no ammonia, we can make neither fertilizer nor explosives, so we'll starve and lose the war!!!!"
"Okay, so you'll need all my notes on my air-extracted ammonia process, then? Here you go."
So Dr. Haber worked with another chemist, Dr. Bosch, for the BASF company, to scale up his process. As Dr. Haber first wrote it, a cup of ammonia could be produced every 2 hours. Not very much. With Dr. Bosch's help, this turned into a veritable flow of ammonia, and Germany didn't starve. It still lost the war, though.
After the war, the allies were very interested in the Haber-Bosch process, and applied it to farming, which also needs ridiculous amounts of ammonia, because plants make their proteins from it. Before, you had to get it from poop, usually seagull poop from Chile. Now, you could have all the ammonia you want and the process is responsible for feeding 1/5th the world today due to massively increased farm yields. Chile was thrown into unemployment, until they discovered that they also have massive amounts of copper.
Dr. Haber went on to invent gas warfare, to extract gold from the sea, and to give the Nazis the finger and move to England. (Significant because he was the sort of patriotic German who they expected to fully back them. ) Dr. Haber died a year later, involved in work in the middle east, but his process is still used today, and still feeding the world.