‘But the multitude of your alien foes will be like small dust,
And the multitude of the terrible ones as chaff that passes away.
Yes, it will be at an instant suddenly,'
From Yahweh of hosts she will be visited,
With thunder and with earthquake, and great noise,
With whirlwind and tempest and flame of a devouring fire,
And the multitude of all the nations that fight against Ariel,
Even all who fight against her and her stronghold, and who distress her,
Will be as a dream, and as a vision of the night.
And it will be as when a hungry man dreams,and behold he eats,
But he awakes and his inner man is empty,
Or as when a thirsty man dreams, and behold he drinks,
But he awakes, and behold he is faint,
And his inner man has an appetite.
So will all the multitude of the nations be,
who fight against Mount Zion.'
However the siege will be lifted because in some way the attackers will, as it were, be blown away as if they were dust, the huge army of terrible ones (‘terrible' is a regular description of those to do with large empires, see Isaiah 25:4-5; compare Isaiah 13:11; Isaiah 25:3; Isaiah 29:20; Isaiah 49:25; Jeremiah 15:21; Ezekiel 28:7 etc.) will be wafted away like chaff. And it will happen suddenly and unexpectedly. A fulfilment of this took place when the Assyrian army withdrew to face the Egyptian army at Eltekeh, and a further fulfilment is found in Isaiah 37:36, when some unknown cause (humanly speaking) wrought death in the camp of the Assyrians causing them to withdraw.
Note the movement from Ariel in Isaiah 29:7 to Mount Zion in Isaiah 29:8, from the pseudo ‘mountain of God/the gods' to the real ‘mountain of God', a sign of the movement in the hearts of many of the people from the unreal to the real, from lack of belief to real belief as a result of their deliverance. Before deliverance, Ariel, afterwards, Mount Zion.
‘‘From Yahweh of hosts she will be visited with thunder and with earthquake, and great noise, with a stormy wind and tempest and flame of a devouring fire.' This is the picture of the God of the covenant, the God of Sinai. This is simply a majestic way of saying that the God of Sinai will come to act on behalf of His people. There too there was thunder and a great noise, there the earth shook, there too there was tempest and the flame of a devouring fire, only the stormy wind was unmentioned (Exodus 19:16-20 with Isaiah 24:17) and that finds mention in the Psalmist's description of the Exodus deliverance (Psalms 77:18), which was thus part of the tradition. It is thus a way of saying that the mighty Creator of Sinai and of the Exodus will come to act in power.
The thought is of what He is rather than of the phenomena being visible. It is God in His power Who acts, even if invisibly. There may be no outward manifestations that can be seen but this will be the spiritual effect. In the account itself it is described as being by the angel of Yahweh (Isaiah 37:36).
We can compare for this how David described Yahweh as coming to his aid in similar language when he was in trouble (2 Samuel 22:8-16). There too he was visualising the unseen power of God. Assyrian kings would also describe their approach in similar language. It was the way of the age.
‘And the multitude of all the nations that fight against Ariel, even all who fight against her and her stronghold, and who distress her, will be as a dream, and as a vision of the night.' The result of Yahweh coming in invisible but genuine power as visualised by the prophet will be that the many nations in the army of Assyria will be powerless against Jerusalem. They will simply have the same effect as a dream or vision of the night, frightening but rapidly disappearing in the morning. The certainty of the dream will give way to the uncertainty of the day. And certainly when the Assyrian army lay down on the awesome night that the angel smote them, they were full of confidence and certainty, and when those who were left awoke it had all vanished. The angel of Yahweh had done His work (Isaiah 37:36).
‘And it will be as when a hungry man dreams,and behold he eats, but he awakes and his inner man is empty, or as when a thirsty man dreams, and behold he drinks, but he awakes and behold he is faint, and his inner man has an appetite. So will all the multitude of the nations be who fight against Mount Zion.' The siege of Jerusalem will seem so threatening, but its threat will turn out to have the potency of a dream. It will be to the enemy like a man having dreams of eating and drinking and then waking to discover he is still hungry and thirsty. It will be an unreality that has no effect in real life. The enemy will go to sleep dreaming of seizing and despoiling Jerusalem, and enjoying all the good things that they will pillage, they will awaken to find that their hopes are in vain. This will be the potency of the international army of Assyria. And why? Because they are not fighting against Jerusalem, nor against Ariel, they are fighting against Mount Zion, the heavenly and earthly dwellingplace of Yahweh, and against the God Who dwells there.