The Egyptians, at the time, were dominated by Assyria, but they then participated in a rebellion instigated by the rulers of Ashdod, in Philistia (Isaiah 20:4). As a result, many Egyptians were led in shame into captivity in Assyria. The "cruel lord" and "fierce king" was evidently Sargon. This prophecy may also have anticipated a similar, and greater, defeat by Babylon under Nebuchadnezzar (Ezekiel 29:19).

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8