The Haber Bosch process for synthesis of ammonia using atmospheric nitrogen was discovered early 20th century and subsequently scaled up into an industrial process in 1910. It was perhaps an important industrial innovation that really made a significant impact in the progress of mankind that we often overlooked.
Before the process was invented, the fertilisers that were produced relied on nitrates from niter deposits and guano (the poop of certain birds and bats). These were all short in supply globally while the demand for nitrates and ammonia increased steadily. Note that at the point of human history, the global population was somewhere around 2 billion.
To a large extent, food resources was soon going to be placing an upper limit on how far the human population could go. The artificial synthesis of ammonia enabled large scale production of fertilisers, revolutionized modern agriculture as well as chemical industry. Nitrates were important for other applications beyond fertilisers, and for a long time, ammonia was an important precursor to that chemically.
Interestingly, in the more recent times, ammonia had become interesting for the fact that it held a fair amount of hydrogen, and is a relatively stable way of holding hydrogen chemically without using carbon. Hence the talks about ammonia as a fuel. It was actually used in 1942 in Belgium when there was a shortage of diesel; engineers had discovered that they could combust ammonia with the help of mixing a small amount of coal. 80 years on from that mini experiment, we are here thinking about how to use ammonia as a fuel again – not because we’re short of hydrocarbons but because we probably over-used it.