A Chemist's affect on history

How could the discovery of a German chemist have caused World War I to have lasted two years longer than it should have done?

How could the same chemist be (indirectly) responsible for 2 billion people living on the planet?

Impossible to believe!!
Want to know more?
Then read:

From fertiliser to Zyklon B: 100 years of the scientific discovery that brought life and death

http://www.theguardian.com/science/2013/nov/03/fritz-haber-fertiliser-ammonia-centenary



Fritz Haber in 1919. Photograph: Topical Press Agency/Getty Images