Decades of civil war during the 1st century BC had contributed greatly to the demise of the old aristocracy of Rome, which was gradually replaced in prominence by a new Italian nobility during the early part of the 1st century AD.
 One such family were the
Flavians, or gens
Flavia, which rose from relative obscurity to prominence in just four generations, acquiring wealth and status under the emperors of the
Julio-Claudian dynasty. Vespasian's grandfather,
Titus Flavius Petro, had served as a
Caesar's civil war. His military career ended in disgrace when he fled the battlefield at the
Battle of Pharsalus in 48 BC.
 Nevertheless, Petro managed to improve his status by marrying the extremely wealthy Tertulla, whose fortune guaranteed the upwards mobility of Petro's son
Titus Flavius Sabinus I.
 Sabinus himself amassed further wealth and possible
equestrian status through his services as
tax collector in Asia and banker in
Helvetia (modern Switzerland)). By marrying
Vespasia Polla he allied himself to the more prestigious
patrician gens Vespasia, ensuring the elevation of his sons
Titus Flavius Sabinus II and Vespasian to the
Around 38 AD, Vespasian married
Domitilla the Elder, the daughter of an equestrian from
Ferentium. They had two sons,
Titus Flavius Vespasianus (born in 39) and
Titus Flavius Domitianus (born in 51), and a daughter,
Domitilla (born in 45).
 Domitilla the Elder died before Vespasian became emperor. Thereafter his mistress
Caenis was his wife in all but name until she died in 74.
political career of Vespasian included the offices of
praetor, and culminated with a
consulship in 51, the year Domitian was born. As a military commander, he gained early renown by participating in the
Roman invasion of Britain in 43.
 Nevertheless, ancient sources allege poverty for the Flavian family at the time of Domitian's upbringing,
 even claiming Vespasian had fallen into disrepute under the emperors
Caligula (37–41) and
 Modern history has refuted these claims, suggesting these stories were later circulated under Flavian rule as part of a
propaganda campaign to diminish success under the less reputable Emperors of the Julio-Claudian dynasty, and maximize achievements under Emperor
Claudius (41–54) and his son
 By all appearances, imperial favour for the Flavians was high throughout the 40s and 60s. While Titus received a court education in the company of Britannicus, Vespasian pursued a successful political and military career. Following a prolonged period of retirement during the 50s, he returned to public office under Nero, serving as
proconsul of the
Africa province in 63, and accompanying the emperor during an official tour of
Greece in 66.
From c. 57 to 59, Titus was a military
Germania, and later served in
Britannia. His first wife, Arrecina Tertulla, died two years after their marriage, in 65.
 Titus then took a new wife of a more distinguished family, Marcia Furnilla. However, Marcia's family was closely linked to the opposition to Emperor Nero. Her uncle
Barea Soranus and his daughter
Servilia were among those who were killed after the failed
Pisonian conspiracy of 65.
 Some modern historians theorize that Titus divorced his wife because of her family's connection to the conspiracy.
 He never remarried. Titus appears to have had multiple daughters, at least one of them by Marcia Furnilla.
 The only one known to have survived to adulthood was
Julia Flavia, perhaps Titus's child by Arrecina, whose mother was also named Julia.
 During this period Titus also practiced law and attained the rank of
In 66, the Jews of the
revolted against the Roman Empire.
Cestius Gallus, the
legate of Syria, was forced to retreat from
Jerusalem and defeated at
the battle of
 The pro-Roman king
Agrippa II and his sister
Berenice fled the city to the
Galilee where they later gave themselves up to the Romans. Nero appointed Vespasian to put down the rebellion, who was dispatched to the region at once with the
 He was later joined by Titus at
Ptolemais, bringing with him the
 With a strength of 60,000 professional soldiers, the Romans quickly swept across the Galilee, and by 68 marched on Jerusalem.
Rise to power
On 9 June 68, amidst growing opposition of the
Senate and the army, Nero committed
suicide, and with him the
Julio-Claudian dynasty came to an end. Chaos ensued, leading to a year of brutal civil war known as the
Year of the Four Emperors, during which the four most influential generals in the
Vespasian—successively vied for the imperial power. News of Nero's death reached Vespasian as he was preparing to besiege the city of
Jerusalem. Almost simultaneously the Senate had declared Galba, then governor of
Hispania Tarraconensis (modern Spain), as Emperor of Rome. Rather than continue his campaign, Vespasian decided to await further orders and send Titus to greet the new Emperor.
 Before reaching Italy however, Titus learnt that Galba had been murdered and replaced by Otho, the governor of
Lusitania (modern Portugal). At the same time Vitellius and his armies in
Germania had risen in revolt, and prepared to march on Rome, intent on overthrowing Otho. Not wanting to risk being taken hostage by one side or the other, Titus abandoned the journey to Rome and rejoined his father in Judaea.
Otho and Vitellius realised the potential threat posed by the Flavian faction. With four legions at his disposal, Vespasian commanded a strength of nearly 80,000 soldiers. His position in Judaea further granted him the advantage of being nearest to the vital
province of Egypt, which controlled the
grain supply to Rome. His brother Titus Flavius Sabinus II, as city prefect, commanded the entire
city garrison of Rome.
 Tensions among the Flavian troops ran high, but as long as Galba and Otho remained in power, Vespasian refused to take action.
 When Otho was defeated by Vitellius at the
First Battle of Bedriacum however, the armies in Judaea and Egypt took matters into their own hands and declared Vespasian emperor on 1 July 69.
 Vespasian accepted, and entered an alliance with
Gaius Licinius Mucianus, the governor of Syria, against Vitellius.
 A strong force drawn from the Judaean and Syrian legions marched on Rome under the command of Mucianus, while Vespasian himself travelled to
Alexandria, leaving Titus in charge of ending the Jewish rebellion.
In Rome meanwhile, Domitian was placed under
house arrest by Vitellius, as a safeguard against future Flavian aggression.
 Support for the old emperor was waning however, as more legions throughout the empire pledged their allegiance to Vespasian. On 24 October 69 the forces of Vitellius and Vespasian clashed at the
Second Battle of Bedriacum, which ended in a crushing defeat for the armies of Vitellius.
 In despair, he attempted to negotiate a surrender. Terms of peace, including a voluntary abdication, were agreed upon with Titus Flavius Sabinus II,
 but the soldiers of the
Praetorian Guard—the imperial
bodyguard—considered such a resignation disgraceful, and prevented Vitellius from carrying out the treaty.
 On the morning of 18 December, the emperor appeared to deposit the imperial insignia at the
Temple of Concord, but at the last minute retraced his steps to the imperial palace. In the confusion, the leading men of the state gathered at Sabinus' house, proclaiming Vespasian Emperor, but the multitude dispersed when Vitellian cohorts clashed with the armed escort of Sabinus, who was forced to retreat to the
 During the night, he was joined by his relatives, including Domitian. The armies of Mucianus were nearing Rome, but the besieged Flavian party did not hold out for longer than a day. On 19 December, Vitellianists burst onto the Capitol, and in the resulting skirmish, Sabinus was captured and executed. Domitian himself managed to escape by disguising himself as a worshipper of
Isis, and spent the night in safety with one of his father's supporters.
 By the afternoon of 20 December Vitellius was dead, his armies having been defeated by the Flavian legions. With nothing more to be feared from the enemy, Domitian came forward to meet the invading forces; he was universally saluted by the title of
Caesar, and the mass of troops conducted him to his father's house.
 The following day, 21 December, the Senate proclaimed Vespasian emperor of the Roman Empire.
Although the war had officially ended, a state of
anarchy and lawlessness pervaded in the first days following the demise of Vitellius. Order was properly restored by Mucianus in early 70, who headed an interim government with Domitian as the representative of the Flavian family in the Senate.
 Upon receiving the tidings of his rival's defeat and death at
Alexandria, the new Emperor at once forwarded supplies of urgently needed grain to Rome, along with an edict or a declaration of policy, in which he gave assurance of an entire reversal of the laws of Nero, especially those relating to
treason. In early 70, Vespasian was still in Egypt however, continuing to consolidate support from the Egyptians before departing.
 By the end 70, he finally returned to Rome, and was properly installed as Emperor.