The Black Death
Ring a ring of roses, a pocket full of posies, achoo! Achoo! We all fall down.
Young children still sing a rhyme about carrying flowers (the smell was believed to hold back the disease), sneezing, and then dropping dead.
But an epidemic of 'flu killed millions in 1918, and even today AIDS is a deadly threat that may devastate the populations of third world countries.
Also this shortage of manpower caused people to think about the creation of new labour-saving devices. and there was a general interest in technology. The stage was set for the Renaissance which began the modern era.
Nevertheless, some doctors thought that the plague was caused by the position of the stars. There was a similar idea about influenza, which comes from the Italian "influence of the stars".
The dead were so numerous that is was not possible to bury them properly, not least because those who treated the bodies for burial often caught the plague themselves. Huge holes, called plague pits, were dug, and the bodies thrown into them.
The disease was already a raging epidemic in continental Europe. As cities and towns across the continent fell to the plague, there was terror and confusion. Both priests and doctors seemed powerless, and many thought that the end of the world had come.
In those days there were very few checks on who went in and out of the country, and as no-one had any ideas how diseases were spread, there was nothing to stop the people of the ship coming into the port.