A pandemic brought home by victorious legions may have killed a Roman emperor
Roman soldiers returning from campaigns in the East around 165 AD carried home a disease, likely smallpox or measles, that spread through the empire for over a decade and killed an estimated 5 to 10 million people. Co-emperor Lucius Verus is thought to have died of it, and some historians believe it also killed Marcus Aurelius himself in 180 AD, weakening Rome's armies and economy for a generation.