What historical fact surprised you when you learned of it?

Most people learn history through school classes that are structured as survey classes, a high level overview of a timeline of events. The purpose is to give you a functional knowledge of the sequence of events in history. Very often, when you dig deeper into a topic, surprising things turn up. For me, it was the U boat activity along the east coast of the United States during WWII, and the use of balloon bombs dropped by the Japanese during WWII.