Zechariah has a context - he & Haggai were raised up about 20 years after the temple rebuilding had been started & discontinued.
See Ezra 5:1-3
They are encouraging the Israelites, led by Zerubbabel & Joshua to get on with the rebuilding - ultimately for Messiah, according to Gabriel's prophecy in Dan. 9.
Many of Zechariah's prophecies are specific for the last week of our Lord's life on earth & the response to the Apostolic preaching:
Zec. 3:9, 6:12-13, 9:9, 11:13, 12:10, 13:1,6,7,
So, how do we understand/interpret Zec. 14 in that context?
The Israelites, in rejecting & crucifying their Messiah have broken the covenant. They looked on the pierced One & mocked him. Now they MUST look on him in repentance & be baptised in the opened fountain. Acts 2 records Peter's preaching & the response of 3000. Acts 3 confirms that Jesus fulfills the covenant, & warns his hearers:
22 For Moses truly said unto the fathers, A prophet shall the Lord your God raise up unto you of your brethren, like unto me; him shall ye hear in all things whatsoever he shall say unto you. 23 And it shall come to pass, that every soul, which will not hear that prophet, shall be destroyed from among the people.
The Jews were becoming non-covenant people. Stephen, by the Holy Spirit, declares them 'uncircumcised.' Acts 7:51 They are the first nation to be destroyed.
There is a new prophetic Jerusalem being built, a new living temple, a new people of God who according to Zechariah:
13:9 And I will bring the third part through the fire, and will refine them as silver is refined, and will try them as gold is tried: they shall call on my name, and I will hear them: I will say, It is my people: and they shall say, The LORD is my God.
14:8 ...
living waters.... must relate to the outpouring of the Holy Spirit according to Jesus' prophecy.
The war against Jerusalem should be understood as war against the new Jerusalem, the redeemed people of God - Christians - and the Jewish leaders, now declared 'uncircumcised' are in the forefront of that war, determined to exterminate the followers of their Messiah.
14:4,5 prophesy the flight of believers from the city. God opens the way, & guards them as they flee. And in v. 9 -
And the LORD shall be king over all the earth: in that day shall there be one LORD, and his name one.
There is no longer a rival city, rival temple, of godless people claiming to be chosen. Jesus is fully vindicated - our LORD Jesus Christ.
Hallelujah!