Flavius Josephus, a First century Jewish Roman historian, Herod the Great fortified Masada between 37 and 31 BCE as a refuge for himself in the event of a revolt. In 66 CE, at the beginning of the First Jewish-Roman War (also called the Great Jewish Revolt) against the Roman Empire, a group of Jewish rebels called the Zealots (kana'im, "zealous ones", commanded by Elazar ben Ya'ir (who may have been the same person as Eleazar ben Simon), who objected to Roman rule of Judea (as the Roman province of Iudaea, its Latin name) took Masada from the Roman garrison stationed there. In 70 CE, they were joined by additional Zealots and their families who were expelled from Jerusalem by the other Jews living there shortly before the destruction of Jerusalem (and the Second Temple), and for the next two years used Masada as their base for raiding and harassing Roman and Jewish settlements alike.
In 72 CE, the Roman governor of Iudaea, Lucius Flavius Silva, marched against Masada with the Roman legion X Fretensis and laid siege to the fortress. After failed attempts to breach the wall, they built a circumvallation wall and then a rampart against the western face of the plateau, using thousands of tons of stones and beaten earth. Josephus does not record any major attempts by the Zealots to counterattack the besiegers during this process, a significant difference from his accounts of other sieges against Jewish fortresses, suggesting that perhaps the Zealots lacked the equipment or skills to fight the Roman legion. Some historians also believe that Romans may have used Jewish slaves to build the rampart, whom the Zealots were reluctant to kill because of their beliefs.
The rampart was complete in the spring of 73 CE, after approximately two to three months of siege, allowing the Romans to finally breach the wall of the fortress with a battering ram on April 16. When they entered the fortress, however, the Romans discovered that its approximately 1000 defenders had set all the buildings but the food storerooms ablaze and committed mass suicide rather than face certain capture or defeat by their enemies (which would probably have led to slavery or execution). Because Judaism strongly discourages suicide, however, the defenders were reported to have drawn lots and slain each other in turn, down to the last man, who would be the only one to actually take his own life. The storerooms were apparently left standing to show that the defenders retained the ability to live and chose the time of their death over slavery. This account of the siege of Masada was related to Josephus by two women who survived the suicide by hiding inside a cistern along with five children and repeated Elazar ben Yair's final exortation to his followers, prior to the mass suicide, verbatim to the Romans.