What does Isaiah 10:16 mean?
Nothing humbles a supposedly strong and self-reliant person quite like illness. No matter how disciplined and successful a person may be, people can quickly become helpless when invaded by the smallest viruses or bacteria. That's what the Lord plans to use, in part, to humble the arrogant king of Assyria.Isaiah writes that the Lord will punish the king's arrogant speech about his own power (Isaiah 10:12). The Lord God will do this by sending sickness among the king's stout warriors. Epidemic illnesses were always a threat in the ancient era. They have always been potent threats among armies who camped in close quarters with large numbers together. A great number of history's war casualties were the result of disease, rather than injury. An unknown virus could quickly tear through such a population. By inducing vomiting and diarrhea, limiting appetite, and reducing the ability to be active, such a virus or illness could quickly shrink the most powerful soldier to a shadow of his former self.
In addition to disease, the Lord will start a flame under the king's glory. He is using the example of a fire that will quickly reveal that the king's supposed control and power to be a weak and flickering thing. The Assyrian king holds no true power in comparison to the Lord. The Lord would not allow the Assyrian king's arrogance to stand. God would take the strength and reputation right out from under the leader of Assyria.
That's exactly what happened. In 701 BC, the Assyrian king Sennacherib had Jerusalem under siege. Then the angel of the Lord arrived and struck down 185,000 Assyrian soldiers in one night. Nothing but body after body was left to be discovered in the morning (2 Kings 19:35). About a hundred years later, Babylon defeated the Assyrian Empire once and for all. All of this was the work of the Lord.