The first historical work by Rome’s greatest historian, Tacitus’ Histories hold a crucial place in the history of Latin literature. Book I covers the beginning of the infamous ‘Year of the Four Emperors’ (69 CE), which brought imperial Rome to the brink of destruction after the demise of the Julio-Claudian dynasty. Galba, Otho, and Vitellius ride the currents of senatorial politics and military sedition to power, while the survivor Vespasian waits just off-stage. After a distinguished public career during the principates of Vespasian and his sons, Tacitus, in middle age, embarked on a historical narrative recording the seering events of the Rome of his youth. This edition provides a Latin text of Book I, a commentary accessible to students of intermediate level and above, and an introduction discussing historical, literary, and stylistic issues. The chance survival of three parallel accounts permits detailed analysis of Tacitus’ selection and stylization of material.