Vespasian's troops brutally conquered the north of Israel, eradicating all resistance. Meanwhile, the Jewish factions – now increasingly concentrated in Jerusalem – moved beyond power struggles into open civil war. While Vespasian merely watched from a distance, various factions of Zealots and Sicarii fought each other bitterly, even those that had common goals. They killed those advocating surrender. Thousands of Jews died at the hands of other Jews in just a few years.

Long before, the residents of Jerusalem had stored provisions in case of a Roman siege. Three wealthy men had donated huge storehouses of flour, oil, and wood—enough supplies to survive a siege of 21 years.

The Zealots, however, wanted all-out war. They were unhappy with the attitude of the Sages, who proposed sending a peace delegation to the Romans. In order to brings things to a head and force their fellow Jews to fight, groups of militia set fire to the city's food stores, condemning its population to starvation. They also imposed an internal siege on Jerusalem, not letting their fellow Jews in or out.

The greatest Jewish sage of the time was Rabbi Yochanan ben Zakkai. He wisely foresaw that Jerusalem was doomed and understood the need to transplant the center of Torah scholarship to another location, to ensure the survival of Torah study after Jerusalem's destruction. He devised a plan that would allow him to leave Jerusalem, despite the Zealots' blockade. He feigned death so that he could be carried out of the city. His disciples carried the coffin out of the city's walls, and Rabbi Yochanan proceeded directly to Vespasian's tent. He entered the tent and addressed Vespasian as "Your Majesty."

"You are deserving of death on two accounts," said Vespasian. "First of all, I am not the emperor, only his general. Secondly, if I am indeed emperor, why did you not come to me until now?"

Rabbi Yochanan answered: "You are an emperor, because otherwise the Holy Temple would not be delivered in your hands.… And as for your second question, the reckless Zealots would not allow me to leave the city."

While they were speaking, a messenger came and told Vespasian that Nero was dead and he had been appointed the new Roman emperor. Vespasian was so impressed with Rabbi Yochanan's wisdom that he offered to grant Rabbi Yochanan anything he wanted as a reward. Rabbi Yochanan made three requests.1 The primary request was that Vespasian spare Yavne – which would become the new home of the Sanhedrin – and its Torah sages.

Rabbi Yochanan thus ensured the continuation of Jewish scholarship after the fall of Jerusalem. Even though they would no longer have a Temple or a homeland, the Jews would always have a spiritual center in the Torah.

In 69 CE, Vespasian returned to Rome to serve as emperor, but first he appointed his son, Titus, to carry on in his stead. In 70 CE, Titus came towards Jerusalem with an army of 80,000 soldiers.