As Tom Holland’s Rubicon and Persian Fire thrillingly demonstrate, the most enjoyable history tells a story, and the Roman historian and politician Tacitus (c AD 56–120), who in his time served as both consul and provincial governor, had no better material with which to start his Histories than the dramatic events that unfolded during the year AD 69, which saw three changes of emperor as various claimants battled it out to succeed the wretched Nero. 

The rebellion against Nero was started in March AD 68 by the governor of Transalpine Gaul, Vindex, and although it was put down, others had been encouraged to try their luck, including Galba in Spain in concert with Otho in Lusitania (roughly Portugal). The Senate opted for Galba, and Nero