On September 13, 81, Titus Flavius Vespasianus, Emperor of Rome (69-81), died of a fever at about the age of 42. From the article:
"Titus was Roman emperor from 79 to 81 CE. On June 24, 79 CE Titus Flavius Vespasianus succeeded his father Vespasian (r. 69-79 CE) as emperor of the Roman Empire. Prior to his ascension to the throne, he was considered by many as “…unpopular and venomously loathed,” yet after becoming emperor, “he became an object of universal love and adoration.” Historians consider the abrupt change in the personality of the new emperor to be a true mystery."