The Fall of Nero and the
Tacitus opens his account of the Year of the Four Emperors on 1 January 69, with the entry into the consulship of the emperor Servius Sulpicius Galba and his henchman Titus Vinius. Though he offers a brief survey of the overall situation, he refers to earlier events only in flashback, and as infrequently and tersely as possible. For what happened in the earlier year we must turn to Suetonius for the fullest account of Nero's last days, to Dio for the only surviving narrative of the revolt of Julius Vindex, the man who set off the events that led to Nero's fall, and to Plutarch for the most comprehensive report on Galba, the man who harvested the fruits of Vindex's endeavors. So why does Tacitus write as he does? Because he was following—and exploiting—the rules for writing history in Rome. An account was organized around an annalistic or year-by-year framework (how smoothly the narrative flowed over or around these breaks depended on the literary skills of the writer), and it was taken for granted that the reader was familiar with the years prior to the chosen starting point or else knew where to find the details. From the starting point onward, each year began with the entry into office of the new consuls on 1 January, since they were—in theory—the highest magistrates or chief executives in the state. And using their names to mark the year had been the custom since that formative event in all Roman history, the foundation of the republic (509 B.C.).
There was another method of indicating the passage of time, reckoning from the year when Romulus supposedly founded the city (753 B.C.). This was less common and more cumbersome. But it could be used to remind the reader how long the city had lasted, especially as there had been occasional predictions that Rome would fall in such-and-such a year. That is why Tacitus brings it up next. The consulship of Galba and Vinius, he says, was the eight hundred and twenty-first year of Rome's existence, so that he can add “and very nearly its last.” In one sense the comment is obvious exaggeration, but every historian was expected to open with dramatic claims to justify his choice of theme and capture the readers' attention. In another sense the remark is highly misleading.