The Year of the Four Roman Emperors explained

Nero, the last emperor of the Julio-Claudian dynasty, had been a controversial figure.

He was accused of many crimes, including murdering his own mother and two of his wives.

His excessive spending had plunged the empire into financial ruin.

Following the Great Fire of Rome in AD 64, Nero had been accused of being more concerned about building a new palace for himself rather than looking after those who had been left homeless by the flames.

By AD 68, the people of the Roman Empire had had enough of Nero and revolted against him.

In particular, the revolt of Gaius Julius Vindex, the governor of Gallia Lugdunensis, in March AD 68, was the last straw that broke the Julio-Claudian dynasty.

He also had the support of the governor of Hispania Tarraconensis Servius Sulpicius Galba.

It's been rumored that both Vindex and Galba had been targeted for execution by Nero, which prompted their revolt.

However, the army of the Rhine-based Lucius Verginius Rufus, who were still loyal to Nero, crushed Vindex's revolt.

Since Galba was not nearby, this left him alone to march on Rome. News of the armies marching towards Rome reached the city and the emperor knew his time was up.

To save himself, Nero fled from Rome in disguise, but only made it just beyond the city walls before his escape route was cut off by approaching enemies.

As a final resort, Nero asked one of his slaves, Epaphroditos, to kill him.

So, the death of Nero on June 9, AD 68, created a power vacuum in the Roman Empire, as there was no clear heir to the throne.

This led to a period of civil war, as three men fought for control of the empire: Galba, Otho, and Vitellius.

With Nero dead, the Roman Empire was without an emperor. The Senate, the group of Roman nobles who had the power to choose a replacement, was divided on who to choose.

Eventually, they settled on Galba. He was an aging but experienced general who was popular with the people in the army.

He was actually proclaimed emperor by his soldiers before Nero's death and the Senate recognized his authority was the previous emperor was gone.

Galba had no living children and he had been previously been passed over for political promotion by Nero.

When news of Nero's death reached Galba, he saw his opportunity to take power. 

When he arrived in Rome with his troops, they declared him emperor.

Galba had support from some influential men. In Africa, Clodius Macer launched a revolution to support Galba.

With the use of only one legion, he cut off Rome's grain supply from Africa, with caused riots in Rome.

Gaius Nymphidius Sabinus, the Praetorian Prefect, asked his praetorians to support Galba in return for a large cash payment.

When Galba arrived at Rome, he adopted the title 'Caesar'. This was the first time 'Caesar' was used to legitimise someone's imperial power, but it would soon become tradition.

However, once in power, people soon turned against Galba, due to some questionable decisions he had recently made.

During his journey to Rome, Galba's armies had plundered communities that did not accept his claims as emperor.

This generated a lot of animosity and hatred in the provinces. He also refused to pay the Praetorians the money promised by Sabinus, which outraged them.

Soon, the Rhine legions that had suppressed Vindex's rebellion declared that they were not loyal to Galba and selected a different leader, Vitellius.

Marcus Salvius Otho, who was the governor of Lusitania, had initially supported Galba's claim to the throne and had marched with him to Rome.

In fact, Otho had a personal vendetta against Nero, since the former emperor had forced Otho to divorce his wife so that she could marry the emperor.

However, Otho had been expecting to be named Galba's heir to the throne as a reward for his part in the revolt's success.

Galba, on the other hand, selected Lucius Calpurnius Piso Frugi Licinianus, rather than Otho.

Angry with this decision, Otho, went to the praetorian guard and bribed them to support him as emperor instead of Galba.

Since Galba had failed to pay them the money promised, the praetorians were happy to support Otho instead.

So, in January 15, AD 69, the short six-month reign of Galba, who had only been in Rome since October, ended when the praetorians murdered him in the Forum.

The Senate confirmed Otho as Galba's replacement and he began his term immediately, having Piso, Galba's probable heir, murdered.

The new emperor was ambitious and greedy, but he did not follow up Galba's death with a comparable degree of bloodshed.

As a result, his reign would also be brief. Vitellius, who had recently been proclaimed emperor by the Rhine legions, was on his way to Rome.

Otho rapidly gathered his own troops and attempted to negotiate with the advancing Vitellius by proposing to make him his adopted son-in-law.

There would be no bargain, however, and the rebel armies entered Italy.

The two armies faced off at Bedriacum, with each one attempting to gain a footing along the Ro River.

Vitellius' legions quickly overwhelmed Otho's center line and gained victory on April 14 AD 69.

Otho, rather than flee and prolong the civil war any longer, took his own life, leaving the Senate with little option but to designate Vitellius as the third emperor in a little over a year.

Vitellius, who had been the governor of Germania Inferior, was declared emperor by the Senate in April AD 69.

However, just like the two men before him, Vitellius' reign was short-lived as he quickly proved to be an unpopular ruler.

Vitellius arrived in Rome and gave lavish banquets, triumphs, and athletic events for his own benefit as well as those of his companions.

This excessive spending put extra weight on the treasury of Rome, which had already been under pressure from Nero's time in power.

Vitellius also committed actions that were seen as dishonouring Roman custom and sensibilities.

For example, the bodies of Romans slain in combat were not given the honors they deserved, and his legions frequently got drunk and caused considerable havoc on their journey to Rome.

However, the Senate was generally pleased with how much autonomy Vitellius gave them, allowing them to control politics with little interference from him.

What Vitellius wasn't prepared for was the fact that there was another person vying for power in the empire.

Vespasian was the governor of Judea (modern-day Israel). He was an influential general who was in the process of successfully crushing an ongoing Jewish rebellion in the region which had broken out in AD 66.

When news of Nero's death reached Vespasian, he saw his opportunity to take power.

His armies, under the command of Marcus Antonius Primus, marched into Italy.

They classed with forces loyal to Vitellius at the Battle of Cremona on October 28.

Vitellius' forces, led by his general Caecina, faced off against those commanded by Antonius Primus.

However, at a crucial moment, a portion of Vitellius' troops defected and fought through the night.

By dawn, the Vitellian forces were in disarray and fled from the battlefield in defeat.

Hearing of Vespasian's soldiers' approach, Vitellius' supporters defended the city of Rome.

Brutal street fighting broke out between the two armies and Vespasian's troops gained the upper hand.

Eventually, Vitellius was captured in the imperial palace on December 20, dragged out to the streets, and killed. His body was thrown into the Tiber.

Vespasian, who had been in Egypt securing grain supply, returned to Rome later in mid AD 70 and was declared emperor.

With the death of Vitellius, the Year of the Four Emperors came to an end. The Flavian dynasty, founded by Vespasian, would rule Rome for the next 27 years.

He proved to be a popular emperor, and he successfully restored order to the Roman Empire.