The Roman attack on Jerusalem came four years into the First Jewish–Roman War.
Triggered by ethnic tensions between Romans and Jews in Judea, the Great Revolt quickly spread throughout the province. Emperor Nero sent four legions, approximately 80,000 soldiers, under the command of his trusted general Vespasian and his son Titus to crush the uprising. By the time Vespasian was recalled to Rome in 69 CE to be appointed Emperor, the Roman forces had driven most of the rebels back to the fortified city of Jerusalem.
Titus moved to besiege the city in early 70 CE, coinciding with Passover. Assisted by the experienced general and former governor of Judea, Tiberius Julius Alexander, he positioned three legions on the western side and a fourth to the east on the Mount of Olives. Pilgrims were permitted to enter the city to celebrate Passover, but the Romans refused to allow them out again. The increase in population placed additional strain on the already-depleted food and water supplies in the city.
Many of the details of the siege were recorded by the Jewish historian Josephus, who had defected to the Roman side after his surrender earlier in the war. Having failed to negotiate with the defenders of the city, but having breached the Third and Second walls, the Romans sought to force the Jews into starvation by erecting a wooden palisade that used every tree in a 10 mile radius.
When the Romans breached the final defences in August the remaining defenders were massacred and the Temple was destroyed, leaving the Western Wall as the only surviving feature.