1918

The Spanish Flu of 1918 may not have been the deadliest epidemic in history, but when paired with the First World War and the social and political turmoil that followed, it was unquestionably the start of one of the worst periods in human history. While the actual figures will probably never be known, the plague is thought to have killed 50-100 million people worldwide, greatly exceeding the total death tolls of both world wars combined. It lasted 15 months and impacted nearly every major country at the time in three waves, each one deadlier than the previous.

The worst part was how quickly it spread; whereas the Black Death spread over decades in many isolated waves around the world, the Spanish Flu killed everything in 15 months. The pandemic coincided with one of the most catastrophic world conflicts in history, making the impacts far more severe than they would have been otherwise. It killed around 675,000 individuals out of a population of 105 million in the United States alone, over ten times the amount who perished in the conflict, and shortened average life expectancy by 10 to 12 years.

The year also marked the beginning of decades of instability for a large portion of the world, fueled in part by the pandemic's devastation and in part by events in Russia, where a popular and brutal rebellion had recently effectively overthrown the emperor. It sparked many anti-imperialist and anti-colonial civil wars all across the world, altering the world for years to come.