The Jewish War is Josephus’ personal account of the Roman siege and destruction of Jerusalem in 70 AD and is indispensable to anyone interested in the New Testament. Once started, it is very hard to put down.
Josephus had been the general in charge of protecting the Galilee from the Roman legions who were on the march. After his capture by Vespasian, who was not yet emperor, he defected to the Roman side and tried to negotiate with the Jews of Jerusalem on its behalf.
His real name was Joseph Matthew but changed it to Flavius Josephus when he was granted Roman citizenship. Flavius was the family name of his patrons, Emperors Vespasian and Titus.
The first reason to read it is that it sheds light on the nature of “mob rule” in 1st-century Palestine. Jesus was the victim of a mob a week after he was hailed a king by one. In Josephus mobs are everywhere and are the source of much of the instability in the region.
The second reason is that you will learn about the incredible intensity with which the Jews believed that religion was a matter of life and death. This was in stark contrast to the Romans and took them by surprise.
The third is that you will find interesting the difference among the various procurators (governors). Some would try to be accommodating to the Jews while others, like Gessius Florus (AD 64-66), simply despised them. The trouble started when Florus, an appointee of Emperor Nero, believed that the Temple in Jerusalem contained immense wealth and he wanted to get his hands on it. His intentional duplicity was meant to provoke the city to rebellion.
The fourth is that there are insights into the bitter relationship between the Jews and the Samaritans. Minor conflicts led to major ones, including massacres and pillage.
Finally, the details in Josephus’ reporting of what happened to Jerusalem in 70 AD are quite shocking, an example of God’s justice and retribution on the scale of that which befell Sodom and Gomorrah. It is also a reminder to the Church today that God will not hesitate to chastise when His people have become unfaithful.
The secret to reading Josephus, in my opinion, is not to start at the beginning, a very dry and detailed accounting of the life of Herod the Great. I would recommend skipping these chapters and start with chapter seven, “Judea Under Roman Rule”. This was when the Jews of Jerusalem started having problems with the Procurators, starting with Pontius Pilate.