Theophylact of Ohrid

"You will hear," He says, "of wars"; these are the wars about which Josephus Flavius also recounts and which took place before the destruction of Jerusalem. The Jews at that time revolted and ceased paying tribute to the Romans, and the angered Romans went to war against them and made constant attacks. "But this is not yet the end" of Jerusalem, for the Romans still showed clemency.

Commentary on Mark ↗

Gregory the Dialogist

Our Lord and Redeemer announces beforehand the evils that precede the perishing world, so that the things to come may disturb us less because they have been foreknown. For missiles that are foreseen strike less forcefully; and we endure the evils of the world more tolerably if we are fortified against them by the shield of foreknowledge. …

Forty Gospel Homilies, Homily 35 ↗

Bede

Now from the time of the Passion of our Lord there ceased not amongst the Jewish people, who chose the seditious robber and rejected Christ the Saviour, either external wars or civil discord; wherefore it goes on: And when ye shall hear of wars and rumours of wars, be ye not troubled. And when these come, the Apostles are warned not to be afraid, or to leave Jerusalem and Judæa, because the end was not to come at once, nay was to be put off for forty years. …

Catena Aurea by Aquinas ↗