Zechariah 14:1-7 is primarily a prophecy predicting the siege of Jerusalem and the destruction of the Temple in AD 70. There is first the natural and then the spiritual. First, God defeated His adulterous Bride, earthly Jerusalem. Then He began to war against the heathen enemies of His true Bride, the heavenly Jerusalem. The warfare spoken of in Zechariah 14:1-2 is about physical warfare and the destruction of physical Jerusalem. Then the warfare of Zechariah 14:3-7 is about spiritual warfare in which the Lord himself fights for spiritual Jerusalem, His Bride, the Church.
The Mt. of Olives is an allusion to where Jesus warned the disciples to flee from Judea when they saw the Roman armies (the abomination that causes desolation) encroaching the city.
The Church historian Eusebius recounts that the Jerusalem Christians were warned in a vision to depart Jerusalem because its destruction was near. According to the Jewish historian Josephus, writing in about AD 75, “many of the most eminent of the Jews swam away from the city” in AD 64 (Jewish War II.20.1). In other words, this “exodus” from Jerusalem occurred three-and-a-half years before the destruction of Jerusalem in AD 70.
Eusebius describes it like this:
“The whole body, however, of the Church at Jerusalem, having been commanded by a divine revelation, given to men of approved piety there before the war, removed from the city, and dwelt at a certain town beyond the Jordan, called Pella. Here those that believed in Christ, having removed from Jerusalem, as if holy men had entirely abandoned the royal city itself, and the whole land of Judea; the divine justice, for their crimes against Christ and his Apostles finally overtook them, totally destroying the whole generation of these evildoers form the earth” (Eusebius, Ecclesiastical History 3,5).
And thus was fulfilled the words of Christ: “Truly, I say to you, this generation will not pass away till all these things take place” (Matthew 24:34) (Taylor Marshall, Eusebius on the Flight from Jerusalem in AD 64).