What does Isaiah 10:28 mean?

The Assyrians (Isaiah 10:5–7) had attacked and destroyed much of Judah. But their destruction of the nation would not be complete until Jerusalem was taken and struck down. The Lord had promised His people that Assyria would not succeed in fully wiping them out (Isaiah 10:20).

This verse begins to explain one possible approach an invading army might take to lay siege to the city of Jerusalem (Isaiah 10:29–32). Scholars reading from the annals of the Assyrian King Sennacherib, as well as 2 Kings 19 and Isaiah 36, insist that this is not the route Sennacherib took on his way to his defeat by the Israelites while laying siege to Jerusalem.

Still, these few verses do describe a fast-approaching army on its way to attack the city. Isaiah begins to follow their route at the town of Aiath, which may be Ai, about ten miles north of Jerusalem. They march through Migron and store their baggage at Michmash. Migron may be a pass between Michmash and Geba. It's possible the army coming to attack Jerusalem left behind their extra supplies at Michmash so they could move faster and get to Jerusalem more quickly.