LDS scholar Keith H. Meservy writes of the events:
At various times during his ministry, Jesus predicted the divine judgments that eventually befell Jerusalem and the Jews. During his last week of mortal life, he not only identified for his disciples the time and the kinds of problems incident to that dark day, but also the ways by which they could avoid suffering the consequences.
The Jews took their major step toward the prophesied destruction when they revolted against the Romans in A.D. 66. Merely four years later, sword, famine, and fire had leveled the city of Jerusalem; soldiers of Rome had leveled Jewish homes vacated recently by the dead and the captives; Jerusalem itself was desolate. Only forty years had passed since Jesus had predicted it. Undoubtedly, many of those who died on Jerusalem's streets had heard Jesus' warnings of disaster and his instructions on how to avoid it. ...
Many accounts of that war were written, but the only one that has survived was written by Josephus, a twenty-nine-year-old commander-in-chief of the Galilean sector, who was in an admirable position to write about it. He knew much of the thinking that had produced it and was an eye-witness to many of its events. He knew the major Jewish leaders and, after his capture, knew also the Roman commanders, Vespasian and Titus. He observed the progress of the war from within the Roman camp and kept track of its details by regular interviews with Roman and captured Jewish participants. He saw the fall of Jerusalem, the burning of its temple, and the leveling of the city. Consequently, his firsthand knowledge of that war makes his record an excellent source for studying the fulfillment of Jesus' prophecy. Especially so, since he felt that God had inspired him to understand what was happening and had preserved his life so that he could tell it.
Josephus, Divine Recorder of the War, Understood It
As the Galilean general, he faced the Romans at the city of Jotapata. When it finally fell after a forty-day siege and he surrendered, he recalled many dreams that he had recently had but had not understood. Referring to himself in the third person, he said: 'There came back into his mind those nightly dreams, in which God had foretold him the impending fate of the Jews and the destinies of the Roman sovereigns." As a priest, he knew how to interpret dreams and knew the prophecies in the scriptures. At that hour he was inspired to read their meaning." Recalling the dreadful images of his recent dreams, he offered up a silent prayer to God. "Since it pleases thee . . . who didst create the Jewish nation, to break thy work, since fortune has wholly passed to the Romans, and since thou hast made choice of my spirit to announce the things that are to come, I willingly surrender to the Romans and consent to live; but I take thee to witness that I go, not as a traitor, but as thy minister."
Josephus' interpretation of the war is so consistent with the prophecy of Jesus that it seems as though he had Jesus' prophecy in front of him as he wrote. I see no evidence, however, that this was the case. And this lack of evidence suggests that, as Josepbus said, he really was inspired to understand the meaning of the war.
Eusebius, early church historian, felt that the similarity between the prophecy and Josephus' history was so striking that it was a testimonial of Jesus' foreknowledge. "How can one fail to be amazed," he wondered, "and to admit how truly divine and surpassingly marvelous our Savior's prescience and foretelling were?" I echo his questions. To understand the prophecy, therefore, one must read Josephus' account of the fulfillment. To understand the fulfillment, one must understand the prophecy.
Today we face a similar predicament. Many religions sense a time of cleansing is coming; a time of tribulation, of woe and calamity. We see in the world today the same sort of wickedness that caused Josephus to conclude that had the Romans...
..."delayed to punish these reprobates," God would have sent an earthquake, flood, or thunderbolt to wipe them out. "For it produced a generation far more godless than the victims of [those former] visitations" (because wickedness enveloped the whole nation).
Of what good would the prophecies of Jesus and the gift of revelation and prophecy enjoyed by the apostles been, had God not intended to spare the Christians from that fate? Even before the Romans advanced on the city, Jerusalem and surrounding environs had become a dangerous place. As Meservy observes:
[Jewish robbers] plundered cities, slaughtered citizens, and forced anarchy upon the country. When the robbers opted for war against Rome, they either encouraged or forced all others to adopt the same course. Finally, at Jerusalem, long before Romans arrived, they were themselves devastating the sacred city. They were the first to burn up the grain supply, bloody the temple courts, and put the torch to sacred precincts. Their unyielding resistance to the Romans contributed to the desolation of the city. Overall, Josephus held them responsible for the destruction of their country, Jerusalem, its temple, and its people.
When Vespasian was called back to Rome to become emperor, the city languished. Completely surrounded and with limited supplies, faction fought faction within the city. People suffered starvation and were forced into cannibalism to stay alive. And when the Romans decided to take the city, Vespasian's son, Titus, now supreme commander, issued strict orders to his soldiers: the Jewish temple was not to be destroyed. Most likely he realized that despite the various factions vying for power, the temple was a unifying element. But when the fighting reached the temple, someone threw a firebrand into one of the doors and soon the building was aflame. Romans broke off to combat the flames and were joined by Jews who also wanted to save it. But Jesus' prophecy stood, and the temple fell and was subsequently razed to the ground, not one stone standing upon another.
The Christians, however, had fled to the north. Jesus had said, years earlier:
The days shall come upon thee, that thine enemies shall cast a trench about thee, and compass thee round, and keep thee in on every side. And shall lay thee even with the ground, and thy children within thee; and they shall not leave in thee one stone upon another; because thou knewest not the time of thy visitation. (Luke 19:41—44.)
When ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.... Let them which are in the midst of it depart out; and let not the that are in the countries enter there into. For these be the days of vengeance, that all things which are written may be fulfilled. (Luke 21:20—22)
So for the Christians to have been caught flat-footed would seem to be unlikely. It also would be unlikely that the apostles, like the prophets of old, would be caught unawares.
For a detailed analysis of the war, see Meservy's article here.