What does Isaiah 10:19 mean?
Isaiah has described the unstoppable, feared, and hated Assyrian Empire as a mighty forest (Isaiah 10:17–18). The Lord, though, is a flame that will burn down that forest. He will bring the arrogant kings of Assyria to their knees. Once this empire ceases to serve the Lord's purpose, it will be like a once powerful warrior who gets a disease and wastes away: only a shadow of its former self (Isaiah 10:16).Now the prophet concludes the forest metaphor by describing the version of Assyria that will remain. When the Lord is done with them only a few "scattered trees" will remain. So few that a child could count them. The great forest will be gone, burned to a pittance to punish the arrogance of its kings.
Although the Lord often uses armies to wipe out armies, He does not need to use them. In 701 BC, the angel of the Lord struck down 185,000 Assyrian soldiers who were surrounding Jerusalem, ending their siege of the city (2 Kings 19:35). In 609 BC, the Lord used the rising Babylonian Empire to defeat the Assyrians, reducing the once-great empire to nearly nothing.