Zechariah 12:
8 In that day shall the Lord defend the inhabitants of Jerusalem; and he that is feeble among them at that day shall be as David; and the house of David shall be as God, as the angel of the Lord before them.

The Angel of the Lord revealed to the Prophet Zachariah that Christ would be born of the House of David. Jesus of Nazareth was raised in the House of Joseph a descendant of King David. The Angel disclosed that Christ would be like God, like the Angel of the Lord in Jerusalem. The Angel goes on to reveal to Zachariah:

Zechariah 12:
10 And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and THEY SHALL LOOK UPON ME WHOM THEY HAVE PIERCED, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn.
11 In that day shall there be a great mourning in Jerusalem, as the mourning of Hadadrimmon in the valley of Megiddon.
12 And the land shall mourn, every family apart;...

it is extremely important to understand this Sentence: THEY SHALL LOOK UPON ME (the Angel of the Lord) WHOM THEY HAVE PIERCED, and they shall mourn for him (Christ). The Angel of the Lord made the proclamation that he would be incarnated in Christ and the People in Jerusalem would cause his divine and heavenly self to be crucified.

Apostle John in the Book of Revelation clarified this Prophecy, he wrote that at the second Coming of Christ they shall see him they have pierced and the Tribes of the Earth (the Land of Israel) shall mourn, lament, wail and be in bitterness because they had crucified the only begotten son of God.

Revelation 1:7
Behold, he cometh with clouds; and EVERY EYE SHALL SEE HIM, AND THEY ALSO WHICH PIERCED HIM: and all kindreds of the earth shall wail because of him. Even so, Amen.

To have a complete understanding of this Prophecy make sure to read:

Second Coming of Christ, exact timing in Revelation
https://www.brighteon.com/6a326ade-3c97-4503-9bf4-7d687453b6df

Revelation 16:
15 Behold, I come as a thief. Blessed is he that watcheth, and keepeth his garments, lest he walk naked, and they see his shame.
16 And he gathered them together into a place called in the Hebrew tongue Armageddon.

Zechariah 12:11 In that day shall there be a great mourning in Jerusalem, as the mourning of Hadadrimmon in the valley of Megiddon.

In the Book of Revelation, for the Second Coming of Christ, Armageddon is mentioned, it means Mountain of Megiddo. The Angel in Zechariah also spoke about a great Mourning in Jerusalem as as the mourning of Hadadrimmon in the Valley of Megiddon.

What does Hadadrimmon mean? Baal was known as Baal-Hadad and also as Baal-Rimmon. All readers can see the Link with the Mountain of Megiddo and the Valley of Megiddo, unfortunately they do not know that Mount Carmel is at Megiddo and also the Brook Kishon is in the plain of Megiddo. Elijah on Mount Carmel prayed God and Fire fell from Heaven upon his offering and he went down to the brook Kishon where he slew 450 Prophets of Baal.

Just as for the Mourning of Hadadrimmon, in 70 AD there was a great Lamentation in Jerusalem, God in His Wrath had judged the false Prophets and religious Leaders of Jerusalem for the Crucifixion of the Son of God and persecution of the Early Church. The Temple and the City of Jerusalem were destroyed...

Related Study:

Spirits of Devils working Miracles
https://www.brighteon.com/4240e36d-0ed2-4c55-a0f1-700353d2feea

Antichrists and the Mark of the Beast
https://www.brighteon.com/12a2728a-5546-4215-9d48-b847d377144d