Zechariah 9:8

And I will encamp about mine house because of the army, because of him that passeth by, and because of him that returneth: and no oppressor shall pass through them any more: for now have I seen with mine eyes.

Zechariah 9 belongs to the later chapters, which have a different historical setting and style from the earlier chapters. That later prophecy looks beyond the restoration from Babylon to the final restoration when Christ comes, so whether those chapters were written before that return or afterward can affect how some of their promises are interpreted. As a prophecy of restoration it was given to encourage the building of the temple and the restoring of Jerusalem under Zerubbabel and Ezra, and that restoration reformation movement is a type of the last reformation.

The verse promises that God will encamp about His house because of the army and because of him that passes by and him that returns, and that no oppressor shall pass through again because He has now seen with His eyes. That encamping protection was effected by God's angel guarding Jerusalem from the army. The promise was fulfilled when Jerusalem escaped unharmed as Alexander passed through Palestine amid his conquest of the surrounding cities, including the Philistine cities. This deliverance came even though the Jews had refused his request for food and he had determined and warned that he would destroy and punish the city. Instead of attacking, the conqueror spared the city from his army and granted the Jews favorable terms.

Beyond its immediate setting the verse looks forward to the Messianic King and kingdom and to the final restoration. In that sense it offers hope to God's people who seek Him and grasp the promises of the Spirit, while the surrounding chapters also foretell judgments on those who reject Him. In that ultimate sense God Himself encamps around His house, the New Jerusalem, to defend it against the army that comes both in passing by and in returning. Then the cunning of Satan and the might of the wicked gathered for battle are of no avail against a city whose defense is the Lord God Almighty watching with His own eyes, and no oppressor shall pass through His people any more. The chapter gives no indication that the Lord would not establish His kingdom when the announced shout was given, so the disciples were left to learn the correction to their expectation only after their disappointment, when they understood that Christ had to suffer before coming in His kingdom.