The Siege of Jerusalem in the year 70 CE was the decisive event of the First Jewish–Roman War, in which the Roman army captured the city of Jerusalem and destroyed both the city and its Temple. The Roman army, led by the future Emperor Titus, with Tiberius Julius Alexander as his second-in-command, besieged and conquered the city of Jerusalem, which had been controlled by Judean rebel factions since 66 CE, following the Jerusalem riots of 66, when the Judean provisional government was formed in Jerusalem.
The siege of the city began on 14 April 70 CE, three days before the beginning of Passover that year. The siege lasted for about four months; it ended in August 70 CE on Tisha B'Av with the burning and destruction of the Second Temple. The Romans then entered and sacked the Lower City. The Arch of Titus, celebrating the Roman sack of Jerusalem and the Temple, still stands in Rome. The conquest of the city was complete on approximately 8 September 70 CE.
Josephus places the siege in the second year of Vespasian, which corresponds to year 70 of the Common Era
Siege
Despite early successes in repelling the Roman sieges, the Zealots fought amongst themselves, and they lacked proper leadership, resulting in poor discipline, training, and preparation for the battles that were to follow. At one point they destroyed the food stocks in the city, a drastic measure thought to have been undertaken perhaps in order to enlist a merciful God's intervention on behalf of the besieged Jews, or as a stratagem to make the defenders more desperate, supposing that was necessary in order to repel the Roman army.
Titus began his siege a few days before Passover, on 14 April, surrounding the city with three legions (V Macedonica, XII Fulminata, XV Apollinaris) on the western side and a fourth (X Fretensis) on the Mount of Olives, to the east. If the reference in his Jewish War at 6:421 is to Titus' siege, though difficulties exist with its interpretation, then at the time, according to Josephus, Jerusalem was thronged with many people who had come to celebrate Passover.
The thrust of the siege began in the west at the Third Wall, north of the Jaffa Gate. By May, this was breached and the Second Wall also was taken shortly afterwards, leaving the defenders in possession of the Temple and the upper and lower city. The Jewish defenders were split into factions: John of Gischala's group murdered another faction leader, Eleazar ben Simon, whose men were entrenched in the forecourts of the Temple. The enmities between John of Gischala and Simon bar Giora were papered over only when the Roman siege engineers began to erect ramparts. Titus then had a wall built to girdle the city in order to starve out the population more effectively. After several failed attempts to breach or scale the walls of the Fortress of Antonia, the Romans finally launched a secret attack.
When Romans reached Antonia they tried to destroy the wall which protected it. They removed four stones only, but during the night the wall collapsed. "John had used his stratagem before, and had undermined their banks, that the ground then gave way, and the wall fell down suddenly." (v. 28)
Titus had raised banks beside court of the Temple: on north-west corner, on north side, on west side (v. 150).
Jews then attacked Romans on the east, near Mount of Olives. Titus managed to drive them back to valley. Zealots set north-west colonnade on fire (v. 165). Romans set on fire next one. Jews wanted it to burn (v. 166).
Jews also trapped some Roman soldiers when they wanted to climb over the wall. They had burned wood under the wall when Romans were trapped on it (v.178-183). Meanwhile in the city, Jews starved and some ate their own children (v. 206-212) "... she slew her son, and then roasted him, and ate the one half of him, and kept the other half by her concealed."
After Jewish allies killed a number of Roman soldiers, Titus sent Josephus, the Jewish historian, to negotiate with the defenders; this ended with Jews wounding the negotiator with an arrow, and another sally was launched shortly after. Titus was almost captured during this sudden attack, but escaped.
Overlooking the Temple compound, the fortress provided a perfect point from which to attack the Temple itself. Battering rams made little progress, but the fighting itself eventually set the walls on fire; a Roman soldier threw a burning stick onto one of the Temple's walls. Destroying the Temple was not among Titus' goals, possibly due in large part to the massive expansions done by Herod the Great mere decades earlier. Titus had wanted to seize it and transform it into a temple dedicated to the Roman Emperor and the Roman pantheon. However, the fire spread quickly and was soon out of control. The Temple was captured and destroyed on 9/10 Tisha B'Av, sometime in August 70 CE, and the flames spread into the residential sections of the city.
