The influenza epidemic of 1918-1919 killed more than 50 million people worldwide. In the United States, approximately 650,000 died. This "Spanish flu" was caused by an influenza A (H1N1) virus that targeted the younger population. The University of Michigan has an absolutely fascinating website, called "The American Influenza Epidemic of 1918-1919: A Digital Encyclopedia," that describes the history of this pandemic in detail. It could take you hours to sift through this treasure of information, and it's worth a visit!
PositiveTip: Increase your knowledge of how the history of medicine helps address contemporary medical challenges.