At the end of the 'Year of the Four Emperors' in which Vespasian ultimately seized final authority, Titus was left with the obligation of completing his father's prior task. Originally authorized by Nero to subdue the Jews several years of internal political strife and civil war limited Vespasian's attention to that cause. With his rise and subsequent cessation of civil hostilities, the Roman armies in the east were free to focus on their goal. Though previously Titus' role in putting down the revolt was mostly non-descript, such as capturing relatively unfortified towns, his obvious position as Vespasian's heir catapulted him into supreme command. Within short order he proved himself to be worthy of the promotion, at least from the Roman perspective. Though his tactics would prove to be brutal, and some of his behavior frighteningly reminiscent of Nero's tumultuous reign, The Jews would quickly find themselves completely overwhelmed and outmatched.
After Vespasian left for Egypt, on his way to claiming the throne in Rome, Titus continued with the task of subduing Jewish resistance. While the countryside was mostly subdued without much difficulty (as most Jewish towns lacked walls and fortifications), Jerusalem was an entirely different matter. Deeply embroiled in political, social and class disorder Jewish zealots associated Roman rule with the elite Jewish aristocracy who failed to understand the concerns of the common people, the city itself was a battleground before Titus even arrived. Josephus, who largely praises his benefactors (Vespasian and Titus) in their conduct of the war, pins the blame of Jerusalem's ultimate capture solely on these zealots for breaking the peace and inviting a harsh response. As Titus arrived, opposed to other regional towns, he found a city strategically positioned upon two hills and surrounded by 3 sets of walls. With four legions he set about laying siege and prepared for a decisive final battle.
While Titus proved himself an able commander, using known siege techniques and strategies and applying them with success, he did little else to merit great praise. Despite the compliments of Josephus, the siege of Jerusalem was largely a learning experience for the future emperor and his energetic leadership was marred only by bouts of inexperience. Even so, in the spring of AD 70, the Romans had breached the city's outer defenses within a span of 4 weeks. All that remained of resistance were those who had holed up within the Temple of Jerusalem, occupying the center of the city. Titus wisely ordered a circumvallation of the Temple to starve out and weaken those who remained. By the end of summer, after a few more grueling months, the Romans managed to breach the Temple's outer wall. In the assaults that followed, all resistance was slaughtered and the Temple itself (the center of the Jewish faith) was burned to the ground. All that remained after Titus' brutal final victory was the single western wall now known as the 'Wailing Wall', which is regarded as the holiest of places and where modern Jews both mourn the loss of the Temple and gather for prayer. As a final insult to those who resisted Roman power, sacrifices to the pagan gods were made in the ruins of the Temple court as proof of Roman religious supremacy.
With the destruction of the Temple and the Jewish war behind him, Titus set about validating and securing his father's newly won throne in the eastern provinces by parading his legions and Jewish captives throughout the region. While doing so, Titus developed a reputation for brutality (throwing prisoners to beasts and forcing them to fight in gladiatorial style) that led to comparisons with Nero. However, Titus' displays proved to be completely tactical in nature and once the point was made, he seems to have discontinued such practices. Other fears of Titus surfaced when he developed a relationship with the Jewish princess Berenice. The sister (or perhaps daughter) of King Herod Agrippa II was strongly allied to the Roman court and she was deeply knowledgeable in eastern politics. On the surface, she seemed an excellent match for the future emperor, but her status as part of a foreign royal family harkened to the days of Antony and Cleopatra. Despite having come to Rome with Titus in AD 75, the general unpopularity of such a relationship forced Titus to eventually dismiss her when he came to power. The interesting point to be found here is that the Roman people still did not view their own 'emperor' as a King in the way foreign monarchs were. The Princeps, even though it functioned with supreme power, still ruled under the guise of a Republican constitution, complete with such offices as Consul and Tribune. Titus himself held the consulship 8 times, indicating its importance at least from the perspective of public perception.
Upon completion of the Jewish Wars and his eventual return to Rome, Titus was groomed as Vespasian's obvious successor and undertook important administrative tasks. In AD 71 he celebrated a joint triumph with his father in celebration of the Jewish victory. He was made joint Censor (responsible for the Census and maintaining the roles of the Senate and the Equite class), and in AD 72 took over the ultimate position of trust, the Praetorian Prefect. Within this role Titus proved his loyalty beyond a shadow of a doubt (there was suspicion that he might try to hurry along his own accession), and took care of much of his father's 'dirty work'. He knew too that his role as heir was secure with Vespasian once commenting that 'either my son shall be my successor, or no one at all.' In June of AD 79, that prophecy was realized, and upon Vespasian's death, Titus was immediately confirmed as the new emperor.