From the spring of 1918 to the early months of 1919, the Spanish flu pandemic ravaged the world, killing an estimated 50 million to 100 million people. It came in three waves, with the last wave being the most deadly.

This flu was unusual in that it was both extremely deadly and seemed to target the young and healthy, being particularly deadly to 20 to 35-year-olds. By the time the flu had run its course, it had killed upwards of five percent of the world's population.

Included below is a fantastic collection of pictures from the deadly 1918 Spanish flu pandemic, including tent hospitals, people wearing preventative masks, a sick child, no spitting signs, and much more.