Question: What Is the Year of the Four Emperors?
The year of the four emperors is A.D. 69. In this year there were four emperors of Rome. Following the death of the last Julio-Claudian emperor, Nero, there was no obvious person to inherit the top position in the Principate, so there was violent competition. The four emperors who all ruled for part of 69 were Galba, Otho, Vitellius, and Vespasian, who survived beyond year's end. With Vespasian came the second imperial dynasty, the Flavians.
In addition to the year of four emperors of Rome, there were also 2 years with even more emperors, the year of the five emperors and the year of the six emperors.
Some ancient writing (in English translation) on the four emperors: