From January 1918 to December 1920, a deadly influenza outbreak infected 500 million people across the world. The Spanish flu pandemic, the deadliest in history, about one-third of the planet’s population—and killed an estimated 20 million to 50 million victims.
More people than any other illness in recorded history died, even more than the total number of deaths in WWI. Masks were the uninfected’s main line of defense. Theaters, churches and other public places were closed for over a year, and many funerals were limited to only 15 minutes.
Why “Spanish”? To read the newspapers of 1918, Spain was hit particularly hard by the virus. Conversely: 1918 was the last year of World War I and, in an attempt to maintain morale, the United States, Britain, France, and Germany suppressed newspaper reports of the illness. Neutral Spain, with no war morale to maintain, did not censor its newspapers; so, to the rest of the world, the flu appeared particularly nasty there.