The unusual disease that came out of nowhere ravaged the world and disappeared humanity has been fighting diseases as long as humanity has existed but spanish flu is quite unique as the world population grew and we became more interconnected throughout history. We fought bigger and bigger pandemics however we learned how to urbanize long before we ever learned how to properly fight these diseases.
This video illustrates how time got mandated in certain areas in 1918. In the past, people told time by using the shadow of the sun and sundials. Eventually, they needed to introduce a new way to measure time because people were increasingly traveling greater distances.