Answer:
Spanish Influenza
A deadly illness took hold as World War One ended and killed an estimated 50 million people globally. On Armistice Day, 1918, the world was already fighting another battle. It was in the grip of Spanish Influenza, which went on to kill almost three times more people than the 17 million soldiers and civilians killed during World War One. Within a few months Spanish Flu had killed more people than any other illness in recorded history. In just one year the average life expectancy in America dropped by 12 years.