I don't write a lot about the Roman Empire, probably because there is so much to dislike about it. Uneven governance, perpetual wars, and a progressive decay of the political system would be some of my reasons. Still we have to remember that the empire lasted 500 years — longer than the republic – and there were periods of prosperity and calm. The death of the empire had many causes, one being the corruptive influence of the king making army. But we get ahead of ourselves.
One of our best sources for history of the empire is Tacitus, who lived from 58-117 A.D. He was a well-educated patrician who rose to consul in 97 A.D. and was also famous as an orator. Tacitus was an eye witness to many of the events he wrote about — rare among Roman historians. Volume one of his histories begins with the year of four emperors – a tug of war between four men who wanted to rule the empire. All four achieved their goal but three got their lives cut short in the bargain. The last of the four, Vespasian, was able to stabilize the empire for twenty three years.
The year 69 A.D. was certainly one of great turmoil in the Roman Empire, starting with Nero's incompetence, which lost him the support of the army. His death on June 9th 68 A.D. resulted from the following sequence of events. In March of that year the governor of Gallia Lugdunensis, Gaius Vindex, rebelled against the taxes levied by Nero. The emperor then ordered the governor of Germania Superior, Lucius Rufus, to put down the revolt. Vindex appealed to Servius Galba, governor of Hispania Tarraconensis, to help him. Galba refused and Rufus defeated Vindex in battle. Rufus' troops proclaimed him emperor but he refused to act against Nero.
Galba's support had grown under the aid of Sabinus, prefect of the Praetorian Guard, and his march on Rome precipitated the death of Nero. Since Nero represented the final member of the Judio-Claudian line, a new line would have to come out of a power struggle. Galba was old (72), and although seasoned in Roman politics he had a reputation for cruelty. To make matters worse he attempted to stabilize the finances of Rome, offending many influential parties in the process.
On January 1, 69 A.D. two legions of Germania Superior refused to take an oath to Galba. The next day Germania Inferior revolted and proclaimed their governor, Vitellius the next emperor. Galba adopted his protégé Piso to try and create a line of succession but this caused him to appear weak. M. Sulvius Otho, former governor of Lusitania, upset that Piso was adopted instead of him, negotiated a deal with the Praetorian Guard to have himself named emperor. Galba, on the way to meet Otho, was assassinated with Piso following shortly after. It was January 15, 69 A.D.
More at The Year of Four Emperorshttp://www.mikeanderson.biz/2012/02/year-of-four-emperors.html