20:1  In the year the general who was sent by Sargon king of Assyria came to Ashdod and took it by combat,

20:2  the Lord had spoken through Isaiah the son of Amoz, saying, Go and ungird the sackcloth from your loins and remove the shoes from your feet. And he had done so, going naked and barefoot.

Isaiah was already in a state of mourning because of the imminent destruction of Egypt, and of course, and of Judea, too because the Assyrians would come through Judea to go into the land of Egypt. And that’s what they were doing here. They had already come and taken Ashdod which was a city on the plain, on their way down to Egypt. So now Isaiah went naked, altogether. And that was a humiliation for him, to go around naked like some weirdo. People would look askance at him and even probably question his credibility as a prophet of God. But he did so, even though it was a test for him to obey God in that instance. Why did he do so? It tells you in the next verse:

20:3  Then the Lord said, Just as my servant Isaiah has gone naked and barefoot for three years as a sign and portent against Egypt and Cush,

20:4  so shall the king of Assyria lead away the captives of Egypt and the exiles of Cush, both young and old, naked and barefoot, with buttocks uncovered—to Egypt’s shame.

So he did it as a sign and portent. As I said before, the words “sign” and “portent” appears here and also in chapter nine, to identify a prophet of God and his disciples. And all of this was to prefigure what the Assyrians would do to the Egyptians, because they would humiliate the Egyptians. They humiliated all those whom they captured. And when they took them away as slaves they stripped and shaved them, to utterly humiliate them. Now, of course, Isaiah himself is humiliated, here, the person Isaiah. For a moment forget about the fact that he’s serving as a sign and portent, and consider how he must have felt. Isaiah, himself, teaches that there comes humiliation before exaltation. He knows the Lord puts people to the test to see if they will obey him rather than follow their own counsel. And so Isaiah did that. And he was obedient for three years, going around naked. He must have been cold, too, in the winter, don’t you think? And maybe be exposed to the rays of the sun in the summertime. I doubt if he sat home all the time, just saying, “I can’t go out there. I’ll make a fool of myself. He was visible. Otherwise it wouldn’t have been a sign and a portent. People would have talked about him. The merchants who went from north to south down to the land of Egypt probably talked about him, and in the land of Egypt, as the word got down there. He did that for three years because within three years the destruction would come upon Egypt, from Assyria. And also the destruction would last for three years. And this is another indication of the three-year warning: from the time the Lord’s Servant begins his mission, at the end time, he serves warning that within three years a similar catastrophe will happen upon the world, a day of judgment—the destruction of the wicked and the deliverance of the righteous. And the destruction, itself, and the cleansing of the earth, and so on, will last for three years, as well. And we see that in chapter thirty-seven; the cleansing endures for three years. This passage kind of appears between the two, and alludes to three years of warning, as well as three years of judgment. So the Assyrians will come even into the land of Egypt, the other great superpower and conquer the land of Egypt, and humiliate Egypt.
Now, those who are ashamed, or those who are shamed, in the book of Isaiah, are those who were prideful. In chapter two, “that which is lifted up in pride” is put to shame and embarrassed and humiliated. This phenomenon would not have happened if there had been no prior pride involved. It’s a covenant curse to be invaded by the enemy and taken away, and to be made captive. So that’s also part of this scenario.

20:5  Men shall be appalled and perplexed at Cush, their hope, and at Egypt, their boast.

People relied on Egypt to assist them against the Assyrians because the Egyptian had vast forces of horses and horsemen, or armaments. Cush was upper Egypt. So Cush is an adjoining nation. And men thought, well we can always rely upon Egypt.
But, guess what? They couldn’t. In that day what shall the inhabitants of the isles say, or isle—as meaning literal island or continent or also just country?

20:6  In that day shall the inhabitants of this isle say, See what has become of those we looked up to, on whom we relied for help and deliverance from the king of Assyria! How shall we ourselves escape?

If that other great superpower is conquered, then how shall we not be conquered?
But, of course, they were relying upon the arm of flesh. They were relying on Pharaoh for help and deliverance instead of upon the Lord God of Israel. Because, what does he do for those who rely upon the Lord? He sends them a savior who will take up their cause, and deliver them, as it says in chapter nineteen. So those who covenant with God, for them there is deliverance. And those who rely upon Egypt, for them there is no deliverance.