Charles Ellicott Commentary Isaiah 20:4

"so shall the king of Assyria lead away the captives of Egypt, and the exiles of Ethiopia, young and old, naked and barefoot, and with buttocks uncovered, to the shame of Egypt." — Isaiah 20:4 (ASV)

So shall the king of Assyria lead away the Egyptians ... — This prediction was not fulfilled in the reign of either Sargon or Sennacherib. Instead, Esarhaddon subdued the whole of Egypt, carried off its treasures, and appointed satraps over its provinces (Budge’s Esarhaddon, pp. 111-129).

The prophet paints a vivid picture of the brutality with which prisoners were treated during a march. What would people say about their boasted policy of an Egypto-Cushite alliance when they saw it result in such a disaster?

It may be noted that Rabshakeh’s scornful phrase, This bruised reed, seems to imply that Assyria no longer feared the power of Egypt. Furthermore, Nahum (Nahum 3:8) speaks of No (that is, No-Amun or Thebes) as having been conquered and its people carried into captivity by the time he wrote.