What year in the history of the Roman Empire is called the Year of the Four Emperors?

The Year of the Four Emperors, 69 AD, was a year in which four emperors ruled in succession. Between June of 68 and December of 69 Galba, Otho, and Vitellius successively rose and fell before the July 69 accession of Vespasian, who founded the Flavian dynasty.